Customer pays for parts/upgrades.
If problem is a virus or a crash that requires a software
customer is responsible for buying a new license if required, unless you have the recovery discs*
Disk provided by the computer manufacturer to you with your computer. If it was on the hard drive, you must have made the disks per their options or it must be available still. Please note that process will put the computer back the way it was when you got it before you installed anything of yours or your data. I will try to recover any data prior to this if I can, but will not guarantee it can be done. If I have to provide an operating system, it will have to be at retail cost.