earlier i was trying to update my windows (service pack, security things, blah blah) and my computer failed to install windows service pack 2 on my computer. the windows help thing literally told me to uninstall the windows service pack 2 i had (which i did) and since then my computer did not start
everytime i try to turn my computer on this list appears:

safe mode
safe mode with networking
safe mode with command prompt
last known good configuration
start windows normally

i chose every single one of these and all it did was restart my computer and come back to this list.
please help!!
thanks