My computer was infected buy some spyware and viruses. I have cleaned them successfully with the help of AVG Antivirus free, but now I have different problem. After cleaning Start button from task bar disappears and now I am able to start programs only from Task Manager. This is really annoying and I would appreciate if you can suggest me what to do to fix this issue.
It looks like some of viruses or spyware programs have damaged your registry. This can present a serious problem which is very hard to troubleshoot correctly and to find a fix. Your best option might be to backup all important data, format hard drive and do a clean Windows install. Trying to find what registry setting are corrupted will require a lot of time and success is not 100 guaranteed and that is why I have recommended clean XP installation.