Sorry to drone on but like most posters seeking answers, you seem to expect those willing to help to have psychic powers of knowing sufficient about your problem to help you without your telling us!
Anyhow, making a number of assumptions which you can refute as and when you can be bothered:
1. You have installed Windows XP SP2 and have encountered some problem or other.
2. To try to recover from your problem, you have tried to use System Restore to reverse the effects of Service Pack 2.
3. You did say that some aspects of Windows XP are not functioning – I assume they were functioning before you installed SP2.
1. Do not install or change anything else before commencing this solution.
2. Reverse the effects of the System Restore that you just did. System Restore will not fully reverse the effects of SP2 – the SP2 upgrade was too comprehensive, and will have included some aspects of the System Restore function itself. If necessary run this from Safe Mode – mash the F8 key on bootup until the menu offering Safe Mode appears.
3. Uninstall the SP2 – you can find it in the Control Panel_Add/Remove Programs list, complete with an uninstall button. It may take some time, but mostly it is reliable in that it strips out enough of SP2 to return your machine to its previous state.
4. If you had some hiccups with SP2, you may find it easier to install, and with much better results if you comprehensively clean your system with anti-spyware tools before you begin, according to a Microsoft KB article that you can google if you are interested. (It goes without saying that the system must be virus free too. If you have no AV installed, either get one, or use an online AV program from either Panda, Symantec or Trend. I find the European (German) Java based Trend solution to be more thorough than the US based Active-X based one). Also, disable any and every background program that you can (especially AV and firewall programs if you have them) while the upgrade is in progress. For safety, physically disconnect from the Internet while your security is lowered!
I hope this helps, but please post with more information if any of the assumptions I have made are incorrect.