There are 2 ways OEM computers are sold:
1) They have a recovery disk, which is specific to the particular model of PC.
2) The hard drive has a recovery partition installed, which takes the place of a recovery disk.
3) A favorite option for HP is to do neither #1 or #2, but instead have a "Create Recovery Disk" app installed by default on the PC. Usually the vendor will offer to create the disks for you... for a fee. Or you can use the app, but they strongly recommend you do it within the first few days of buying the PC.
If your PC was sold under option #1, then you probably have the disk somewhere...it just may not say "Windows" on it. If you don't, then you can look on Amazon or eBay to see if anyone is selling one. You'll have to make sure it's for the identical model for your PC (i.e. if your PC is model "DX4837" & they're advertising a disk for model "DX4839", don't expect it to work with your PC).
If your PC was sold under option #2, then you should still have it...unless you somehow managed to delete the recovery portion. That is not, BTW, something easily done by clicking on the wrong icon. You have to delve into disk management deliberately in order to get rid of that stuff. If this is the case...your best bet is to buy some disk cloning software (preferably one that will let you clone the data to "dissimilar" hardware).
If your PC was sold using option #3... so sorry that you didn't take the time to follow the instructions for creating the recovery disks in the first place. However, you can probably still use disk cloning software (as for option #2).