Can anyone tell me the model of this watch? i cant find it anywhere
how can i fix it if it stops? please help me

 

Maybe a moderator can move to Longines section?

Likely has no model name, as these late 70's/early 80's usually didn't. I can't magnify the photo above enough to read the movement number at the bottom of the dial, but would guess it's a 990 (it will say '990' as the first number). That is a nice movement that any good watchmaker will be able to service. Cool watch in a late 70's sort of way. Appears to have an integrated bracelet, which can be trouble when it starts to break. These were usually gold-plated watches.