problems with volume shadow copy service

Hi
I recently tried to create a restore point and it failed due to the volume
shadow copy not working error 0x81000202 but subsequently on using vssadmin i
see that it is not installed on my computer anymore. I have vista home
premium which was installed on a new pc 5 months ago.
This is a problem as i will not be able to intall vista sp1 on my computer
as i cannot make a restore point or backup. Sure i can back up the system
with acronis true image or some other such program but vista is not working
properly. Any suggestions