When a now famous singer returns to his hometown after years, an old estranged friend and former band mate, now unsuccessful has to re-create an old gig of their band to get in contact with his friend again.

Who is the protagonist here? The character who has made it? Or the one who has failed?

And what is so important about re-establishing contact? What are the stakes? That is, what does the protagonist stand to lose if he fails? What does he stand to gain if he succeeds?

Agree, dig the glory days band reunion idea.
I do struggle with your protag(s), appears to be a buddy show that jumps on the opportunity when their famous singer friend arrives? Please clarify that.

Leaning towards:
“When their now-famous singer tours through their hometown, two washed-up former bandmates reunite the estranged members in hopes of wooing him into recreating the career-launching gig that never happened”

Take care.

I like the premise.

The logline needs to tighten up a bit. But it isn't that far off.