Vista - update wont install ,cant use safe mode

Last week, I was unable to install Microsoft updates. They failed every time. I overcame this by doing a system restore to an earlier date before the previous updates. They then installed. However I was left with Microsoft Net framework 3.5 Service pack 1 which failed to install. I went to Microsoft download site and downloaded from there.
The my troubles started, in that now on opening my machine it tries to configure these updates and says on screen "configuring 3 of 3" gets to 87% then closes automatically and restarts the process overagain.
I tried to open in "safemode" but exactly the same thing happens. Is there anything I can do to stop this, or am I forced in to doing a restore to factory settings, or I note that I have another option of "last known good configuration (advanced)". As I am not advanced this causes me concern. Any suggestions are most welcome.

Yes you can try it if also fail use System Restore by using DVD Vista or (I understand
you don't have it) you can use special recovery disk instead

see:
System Restore - undo
Create a Recovery Disc

Good configuration did not work, i don't have Vista DVD ,I will go down the recovery disc path.
Thanks for your kind assistance

Thanks for advice,I have a working machine again,technical support from Novatech (makers of my PC) talked me through system restore via " repair your computer" .
The updates of March 10th still fail to install.

Try methods from this tutorial here
http://www.vistax64.com/software-too...air-tools.html

If above advices no help find in C:\Windows file WindowsUpdate.log and attache here

Thanks for your suggestions ,I will try to sort it out soon.
I confess to being a little wary after my recent difficulties but will give it a go.

After two weeks of trying to effect a repair,with considerable help from Microsoft Support,it transpired that my operating system had somehow been corrupted.
The end result was a restore to factory settings,with everything backed up,I am back to normal.
The reset was easy and with backups installed the whole task was over in about an hour.
I'm just so glad I had every thing important backed up.
Moral = If you have not got a back up do it before its too late