|You haven't supplied enough information.|
What is/are the symptoms of your problem(s)??
Depending on what they are, you may not need a Rescue disk or similar.
If the computer boots but you can't get Vista to start up normally, have you tried booting into Safe mode?
(Remove any bootable disks you have in drives. Press F8 repeatedly while booting - don't hold down the key - select Safe mode from the boot choices menu that appears.)
"I do not have the back up disk for my window vista HP pavillion slimline desk top computer"
We've heard similar from a zillion other brand name system users.
Why don't you??
If you have lost it/them or bought your computer second hand and didn't get it/them, you can probably order it/them from the HP site. Look in the software downloads for your model on the HP site - if it/they is/are available there is a link there to where you order it/them. You will need the exact specific model found on the label on the outside of the case. E.g. a two disk set cost me ~$45 recently, for a HP XP computer.
If you can't get into at least Safe mode, if the computer boots but you can't get Vista to start up, you must have either the disk(s) that came with or are for the computer, or you must have a regular or preferably an OEM Vista DVD in order to possibly fix your problem(s).