make sure you the branch you are pushing to and the branch you are in locallly
are the same, {if there is no tracking relationship between the two establish one}
use command git push -u origin <branch>
/if that doesn't work you can do it forcefuylly using
git push -f origin <branch>
do a git status to confirm if there are indeed any commits that need to be pushed
do a git push to the origin master again