Find and download a free program called ieradicator. Run it to fully eradicate IE. Then reinstall. You'll need at least the setup program on your hard disk, and preferably the whole of IE on a CD (most ISP's give such CD's away).

If you've got nothing of such first download mozilla (other browser) from and use that to download IE from microsoft. If download doesn't work either, due to IE problems, find a friend with a CD-burner and download it there.

This might work, unless the underlying cause of the problems is virus or spyware damage elsewhere in your system. A full scan might be a good idea, as soon as you've got a browser up and running.

Hope this helps.