I have an older macbook air and it keeps restarting and wont load pass the apple sign, whats wrong with it?
When powering up your MacBook Air, hold down the Command key and the R key. This will start the OS X Recovery system. From there you'll be able to reinstall the system (you can keep your installed programs and your data files) - which could fix the problem.

If the recovery system does not come up, it could be because your computer is too old to have it (i.e. it is older than the 2008 model). In that case, let us know which model of the MacBook Air you've got.

Another thing to try is to use another computer to create a OS X Recovery USB drive. You can find the download and instructions for that here:

http://support.apple.com/kb/DL1433

If neither works, you either have a hardware defect of some sort or need someone a little more trained on reloading the OS and triaging whether your boot issue is hardware or software. Lastly, the computer people will likely just systematically go through the following article and there's no reason you can't start that process as well and ask here when you end up with a failed step.


http://support.apple.com/kb/TS2570 - Troubleshooting a Mac that starts to a grey screen