Are you using one mic? Or plugging a single guitar cord in? Because those are mono sources.
Are you recording to a stereo track in the computer? Record a mono source into a stereo track and it will only come out of the left or right whichever you tracked it into. So you should be recording mono tracks and making certain that you have not panned it to either side and it should come out of both speakers.

im using one mic on my tascam has a mono off and on switch should i use it all try what u said right now thanks

ok so instead of stero i put us tascam analog L and it worked also put mono on to interface. so after im done do i mix to stereo. does it matter if i put L or R when i record

I have no idea what analog L is as far as tracking goes. If your tracks are recorded in mono (they really should be) they are usually, and always could be, routed out to a stereo output (this is something that you set up in a project in the very beginning, READ your manual.)
If we take three mono tracks for example, a guitar track, piano, vocal. If we pan the guitarist almost all the way to the left 80% of the sound will come from the left speaker 20% from the right. Pan the piano almost all the way right and again you get 80% right and twenty % left, leave the vocals untouched and they will come equally from both left and right thus we create a stereo image that makes you feel as though the guitarist was stage left, piano stage right and vocalist center stage. This is much more complex when mixing twenty or more tracks but the idea is the same. READ about panning in your manual, in fact read your manual you can not learn how to use your software (DAW) by posting individual questions in a forum.