Did you make any major changes to your system the last time you used it? Install/uninstall any programs, run any programs, etc? Are you using Windows? If you're using XP, you can try and restore your computer to an earlier time using the Restore feature START>Programs>Accessories>System Tools>System Restore OR you can use your Windows XP setup disc to repair your installation of Windows. Just put the installation disc in and follow the on-screen prompts for REPAIRING an installation of Windows. Which fonts are missing? All of them? You may have inadvertently switched the language Windows uses (or you may have a virus on your computer that's messing with your settings, registry entries, etc). Check Control Panel>Regional and Language options and make sure you have the correct language selected in each dropdown menu. Have you scanned your computer for malware (adware, spyware, viruses)? If neither of the things I mentioned above fix the problem, then it's possible the problem is being caused by a malicious program. Check the processes running on your computer against the database at www.processlibrary.com (bring up the Windows taskbar and select the "process" tab). You can enter each process into the search bar @ processlibrary and it will let you know if it's a valid process or if it's associated with a malicious program. If you come across something that's been tagged as a threat, the webpage will give you more information on the threat and how to remove it from your computer.

I'd go with the System Restore. It seems to correct most problems.