Hvis det gamle ikke virker, tager jeg det nye.

Hvis introduces a condition: if X happens, then Y happens.

So in this sentence, Hvis det gamle ikke virker ... means there is a condition that must be checked first.

A very common learner confusion is hvis vs om:

• hvis = if in a conditional sense
• om = usually whether, or sometimes in/about/around, depending on context

So you say:

• Hvis det gamle ikke virker, tager jeg det nye.
• Jeg ved ikke, om det gamle virker.

The first is conditional. The second means I don’t know whether the old one works.

Because the sentence begins with a subordinate clause: Hvis det gamle ikke virker.

In Danish, when a subordinate clause comes before the main clause, it is separated from the main clause with a comma:

• Hvis det gamle ikke virker, tager jeg det nye.

So the comma marks the boundary between:

• the if-clause
• the main statement

This is very similar to English punctuation in sentences like If the old one doesn’t work, I’ll take the new one.

Because this is a subordinate clause, and Danish word order changes in subordinate clauses.

In a subordinate clause, ikke usually comes before the finite verb:

• Hvis det gamle ikke virker

Compare that with a normal main clause, where ikke usually comes after the finite verb:

• Det gamle virker ikke.

So:

• main clause: verb + ikke
• subordinate clause: ikke
  • verb

This is one of the most important word-order patterns in Danish.

Because Danish main clauses follow the V2 rule: the finite verb normally comes in the second position.

Here, the whole Hvis det gamle ikke virker clause comes first. That entire clause counts as the first element. So the verb in the main clause must come next:

• Hvis det gamle ikke virker, tager jeg det nye.

If you put the main clause first, then the order is normal subject-verb order:

• Jeg tager det nye, hvis det gamle ikke virker.

So the change to tager jeg is not random; it is a standard Danish word-order rule.

Yes, you can think of a noun as being understood from the context.

Det gamle and det nye are adjectives being used like nouns. In English, this is often translated as:

• the old one
• the new one

So the sentence is talking about some previously understood thing, such as a tool, battery, phone, key, system, etc., without repeating the noun.

This is very common in Danish.

For example, if the omitted noun were batteri, you could understand:

• det gamle batteri
• det nye batteri

But once the noun is already clear, Danish can just say:

• det gamle
• det nye

Because they are in the definite adjective form.

In Danish, adjectives often take -e when they are used with den, det, or de, or when they are otherwise definite:

• det gamle
• det nye

That is why you do not get:

• det gammelt
• det nyt

Those forms are wrong here.

Compare:

• indefinite neuter singular: et gammelt hus, et nyt hus
• definite / with article: det gamle hus, det nye hus

Since det gamle and det nye mean something like the old one and the new one, the -e form is required.

Virker is the present tense of virke.

In this sentence, it means works or functions.

So it is used for something that may or may not operate properly:

• a machine
• a device
• a method
• a solution
• medicine
• a plan

Be aware that virke can also mean seem in other contexts, but that is not the meaning here. Here the natural meaning is work / function.

Tager is the present tense of tage.

Its basic meaning is take, but in this kind of sentence it often means something more like:

• take
• use
• go with
• choose
• switch to

So the idea is not necessarily just physically grabbing something. It can also mean choosing the new option because the old one does not work.

That is very normal Danish usage.

No. It depends on the gender and number of the noun that is understood from context.

You can have:

• den gamle / den nye for a common-gender singular noun
• det gamle / det nye for a neuter singular noun
• de gamle / de nye for a plural noun

So this sentence most naturally suggests either:

• a neuter noun is being left out, or
• det is being used for a general thing

For example:

• den gamle if the hidden noun were a common-gender word
• det gamle if the hidden noun were a neuter word

Both verbs are in the present tense:

• virker
• tager

This is normal in Danish. Danish often uses the present tense for real conditions and even for near-future meaning.

So tager jeg det nye can mean something like:

• I take the new one
• I’ll take the new one

The exact English translation depends on context. In many cases, English prefers I’ll take the new one, but Danish does not need a separate future form here.

Yes, in many contexts you could.

Both virker and fungerer can mean works / functions.

A rough difference is:

• virker is very common and broad
• fungerer can sound a little more like functions properly

In everyday Danish, virker is often the more natural choice for many ordinary situations. But fungerer is not wrong if the context fits.

So:

• Hvis det gamle ikke virker, tager jeg det nye.
• Hvis det gamle ikke fungerer, tager jeg det nye.

Both are understandable, but virker is especially common.