There isn't quite enough to go off here so I'm going to go out on a limb.
My guess is that you had the repo and everything was fine. Then you got a new computer, downloaded the files, are able to change and push but (as you mentioned) no credit the work you did. If that's the case, what is likely is that you have a config problem. Github is crediting someone or something else, just not you.
How to fix it:
git config --global user.name "<your github user name>"
git config --global user.email "<the email account you have for github>"
How to tell:
I put this last because the fix is simply easier to do.
On your computer and in the repo that isn't getting credit type
git blame <file you've made recent changes>
. Look for two different names. Unfortunately, it doesn't show email but use this as a first go. If you don't see any differences and there is a chance (hence the reason to simply do the fix first) no email is configured or the two emails differ.
git blame --line-porcelain <file you've made recent changes>
From there carefully look at the first two lines (author and author-mail) and look for discrepancies.