Linux deleted

[Peter L]

Well my brother in college needed a laptop to use for the last two weeks before he comes home. I gave it to him and he decided to install Windows and erased Linux. Well that sucks, but he said there is still an os.old partition and he can access the files...so how can I go about restroing it without losing much data. I know I'll lose all my customizations, programs, and probably bookmarks (which will suck badly).