I have nissan sentra 1992gxe.i turn on the ignation but it doesn't start doesn't even crank.is it starter or fuse or something else.

Try turning on the head lights to see if they are bright if they seem dim try battery cables for corrosion lose cables weak battery or a bad solenoids starter relay

It sounds like the starter. Take a rubber mallet or a small hammer and beat the starter a few times not really hard like it owes you money, but hit it good. If the car starts after this your starter is stuck and needs to be replaced. Now this might not work, the starter can be so bad that nothing like this will help. Take it off go to your local parts store and they can test it for you. There should not be a fuse anywhere on the starter wire. O yeah make sure the battery is good and charged up. A low battery will do this too.