Skjárinn varð skemmdur þegar hann datt á gólfið.

Skjárinn means the screen. Icelandic usually adds the definite article to the end of the noun instead of using a separate word like English the.

• skjár = screen
• skjárinn = the screen

So the -inn ending is the suffixed definite article.

Varð is the past tense of verða, which means become or get.
So varð skemmdur literally means became damaged or got damaged.

This is very natural in Icelandic when describing a change of state:

• Hann varð þreyttur = He became tired
• Skjárinn varð skemmdur = The screen got damaged

If you used var skemmdur, that would mean was damaged, which describes a state, not so clearly the moment of change.

Skemmdur agrees with skjárinn in gender, number, and case.

• skjár is masculine
• it is singular
• here it is in the nominative

So the participle/adjective appears as skemmdur, the masculine singular nominative form.

Compare:

• skjárinn varð skemmdur = masculine
• hurðin varð skemmd = feminine
• borðið varð skemmt = neuter

It is originally a past participle of the verb skemma (to damage, ruin), but in this sentence it behaves much like an adjective.

So varð skemmdur is structurally became damaged.
English learners often think of this as halfway between:

• an adjective: damaged
• and a passive-like form: got damaged

Both ideas are useful here.

Because skjár is a masculine noun, the pronoun referring to it is hann.

In Icelandic, pronouns follow grammatical gender, not just natural gender. So even though a screen is not male, it still takes hann because the noun is masculine.

• skjár → masculine → hann
• hurð → feminine → hún
• borð → neuter → það

Both are past tense forms.

• varð = past tense of verða (become)
• datt = past tense of detta (fall)

So the sentence describes two past events:

1. the screen got damaged
2. it fell onto the floor

This is about how á works with case.

With á:

• accusative usually expresses movement toward / onto
• dative usually expresses location on

So:

• á gólfið = onto the floor / to the floor
• á gólfinu = on the floor

Because the screen fell onto the floor, Icelandic uses the accusative: gólfið.

Just like skjárinn, gólfið has the definite article attached to the noun.

• gólf = floor
• gólfið = the floor

The exact form of the suffixed article changes depending on the noun’s gender and form.
Here gólf is a neuter noun, so the definite form is gólfið.

Because þegar introduces a subordinate clause: when he/it fell onto the floor.

In this kind of clause, Icelandic normally keeps the subject before the verb:

• þegar hann datt á gólfið

This is different from main-clause word order, where Icelandic often has verb-second patterns.
So for learners, it is helpful to remember:

• main clause: word order can shift because of V2
• subordinate clause after þegar: subject + verb is very normal

Here it means when.

It introduces the event that caused the damage:

• Skjárinn varð skemmdur þegar hann datt á gólfið
• The screen got damaged when it fell on/onto the floor

In some contexts þegar can also be part of meanings related to time more generally, but in this sentence when is the clear translation.

Grammatically, the most natural interpretation is yes.
Since hann is masculine singular, it matches skjárinn.

So the sentence is understood as:

• The screen got damaged when it fell onto the floor.

In a larger context, a masculine noun mentioned earlier could in theory also be the antecedent, but by itself this sentence strongly points to skjárinn.

Yes. Datt is an irregular past tense form of detta.

• detta = to fall
• datt = fell

This is a very common verb, so it is worth memorizing as a separate form rather than trying to build it mechanically.

Yes, that translation is possible, but got damaged is often closer to the Icelandic feeling here.

That is because varð skemmdur emphasizes a change of state:

• got damaged
• became damaged

English was damaged is not wrong, but it can sound slightly more neutral and less focused on the change itself.