I can not open the PC to work it show a couple of messsages:

Disk boot failure insert disk and press enter.

ST3400820AS: Hard disk failure is imminent please backup your hard disk and have it replaced.

This always shows up then I have to press F2 then it goes blank..

Your hard drive or hard disk is kaput and needs to be replaced. There is nothing you can do at this point except replace it and try and back it up if you can. If you have a local computer repair place near you they could possibly back up your hard drive and save it but more than likely the info on it is corrupted by now. It's worth a try though.

What can I do to make my PC to work? I can not open the PC to work it show a couple of messsages: Disk boot failure insert disk and press enter. ST3400820AS: Hard disk failure is imminent please backup your hard disk and have it replaced. This always shows up then I have to press F2 then it goes blank.. I do not have the recovery disk and I can not make one since the PC is not working... help

Recovery disc kits can be ordered from the HP web site (http://www.hp.com) in the support section for your product model under software and downloads. A new hard drive can be purchased locally or online.

Generally speaking, you can pop in a new hard drive and do a fresh install. When you are all done, hook up your old one and copy any personal data. If the drive is failing and its just too many bad sectors, you can usually recover most all of your data, just system files get corrupted because that part of the hard drive is used so much.

If, however, your hard drive is failing due to a bad head, or some other reason (ie. Clicking and whirring) you usually don't have the best of luck copying files. Sometimes putting it in the freezer for an hour will give you about 15 to 20 working minutes where it will work decently.

There are professional recovery places, however the harder it is, the more it'll cost you.

https://www.askmehelpdesk.com/windows/recovery-disk-hp-pavillion-s3200z-desk-top-434124.html#post2173546

Well gee, why didn't you make the disks when you first got the PC?

The question now is whether it's a drive failure or a drive interface failure. So first you need to get the recovery disks as scleros said. Then buy a new driver and use the Recovery disks,

P.S. merged your threads, please don't start a new thread for the same question.