permission inheritance

Hi All,

I have one site collection and below that various sub sites are there, suddenly i landed up with a situation where one of the subsite owner was not able to view the site, he was getting access denied message while accessing. Subsites were had unique permission.

I added him to the Site owners group but next day when i checked his name was not there, it was not appearing there. Then i decided to try the inherit permission option.

At first, i inherited only for one subsite then he was able to access the site,  and i inherited the permission to all other sub sites as well. Now user is able to access all the sites.

Suddenly i came to know because of that permission inheritance some other users lost there access to some other subsites. Now i need to roll back to the previous permissions.

What if i do stop inheriting , it will come back to its earlier permission levels..???

Version used: SP 2010

Please help..

Thanks