Telefonul meu nu merge acum.

Because Romanian usually attaches the definite article to the end of the noun.

• telefon = phone / a phone
• telefonul = the phone

So telefonul meu literally means the phone of mine, but in natural English that is simply my phone.

This is a very common Romanian pattern:

• băiat = boy
• băiatul = the boy
• carte = book
• cartea = the book

In Romanian, possessive adjectives often come after the noun, especially when the noun is definite.

So:

• telefonul meu = my phone
• literally: the phone my

This is normal Romanian word order. English puts the possessive first (my phone), but Romanian often uses:

• noun + definite article + possessive

Examples:

• fratele meu = my brother
• casa mea = my house
• prietenii mei = my friends

Because telefon is a masculine singular noun.

Romanian possessive forms change to match the gender and number of the noun:

• meu = my, for masculine singular
• mea = my, for feminine singular
• mei = my, for masculine plural
• mele = my, for feminine plural

So:

• telefonul meu = my phone
• cartea mea = my book
• pantofii mei = my shoes
• cărțile mele = my books

Nu is the normal Romanian word for not.

It goes before the verb:

• merge = works / goes
• nu merge = does not work / is not working

So:

• Telefonul meu merge. = My phone works.
• Telefonul meu nu merge. = My phone doesn’t work.

This placement is very standard in Romanian: nu + verb.

Yes—a merge literally often means to go, but it is also very commonly used to mean to work / to function.

So depending on context:

• Merge la școală. = He/She goes to school.
• Telefonul merge. = The phone works.
• Nu merge internetul. = The internet isn’t working.
• Mașina nu merge. = The car doesn’t work / won’t run.

In your sentence, because the subject is telefonul meu, merge is understood as works / functions.

It is present tense, third person singular, from the verb a merge.

Because telefonul meu is a third-person singular subject (my phone), the verb form is merge.

Basic present forms of a merge:

• eu merg = I go / I am going
• tu mergi = you go
• el/ea merge = he/she/it goes
• noi mergem = we go
• voi mergeți = you (plural) go
• ei/ele merg = they go

Here, telefonul meu behaves like it, so Romanian uses merge.

It can suggest either, depending on context, but with acum it usually means:

• My phone isn’t working right now
• or My phone doesn’t work at the moment

The word acum means now, so it gives the sentence a present, immediate feeling. Without acum, Telefonul meu nu merge could sound more general.

Compare:

• Telefonul meu nu merge. = My phone doesn’t work / My phone isn’t working.
• Telefonul meu nu merge acum. = My phone isn’t working now / at the moment.

Yes, Romanian word order is somewhat flexible, and acum can move for emphasis.

All of these are possible:

• Telefonul meu nu merge acum.
• Acum telefonul meu nu merge.
• Telefonul meu acum nu merge.

The most neutral version is usually Telefonul meu nu merge acum.

Changing the position of acum may slightly change the emphasis:

• Acum telefonul meu nu merge = Right now, my phone isn’t working.
• Telefonul meu nu merge acum = My phone isn’t working now.

Yes, absolutely.

• nu merge = doesn’t work / isn’t working
• nu funcționează = doesn’t function / isn’t functioning

Both are correct, but nu merge is more common and conversational in everyday speech. Nu funcționează sounds a bit more formal or technical.

So:

• Telefonul meu nu merge acum. = very natural, everyday speech
• Telefonul meu nu funcționează acum. = also correct, slightly more formal

No, it is not missing here, because the subject is already expressed: Telefonul meu.

Romanian does often omit subject pronouns like eu, tu, el, ea when they are not needed, because the verb ending usually shows the person. But in this sentence, the noun phrase itself is the subject:

• Telefonul meu = my phone

So there is no need for a separate pronoun.

You would not say something like Telefonul meu el nu merge acum. That would be unnatural.

A rough English-style pronunciation is:

te-leh-FOH-nool meh-oo noo MER-jeh ah-KOOM

A few helpful notes:

• telefonul → the -ul ending is the attached definite article
• eu in meu is pronounced like a quick eh-oo
• g in merge sounds like the j in measure, not like the g in go
• u in nu and -ul is a clear oo sound

A more careful breakdown:

• te-le-fo-nul
• meu
• nu
• mer-ge
• a-cum

Not exactly, but it may feel that way to an English speaker.

Romanian often combines:

• a definite noun
• plus a possessive adjective

So telefonul meu is literally closer to the phone my, but the correct natural English translation is just my phone.

This is one of those places where Romanian structure differs from English. You should learn telefonul meu as the normal Romanian way to say my phone, not as a word-for-word English pattern.