It may depend on which version of linux but this forum should be able to help
http://www.linuxquestions.org as it deals with a huge range of different versions of linux but is dedicated to linux support.
It might be worth popping along to
http://distrowatch.com to see if you recognise which of those versions of linux you are using. If you see your version listed down on the right-hand side then click on it and navigate to the "User Forums" for your version of linux. They should be able to give much better help in there.