Computer “repairing C drive”

[JACJ54]

My computer, on its own, began running a program indicating it was doing disc repair.   Fixing (C:).  It goes thru stages 1, 2 and 3.    Says it may take over an hour.  This has been running for at least 18 hours.   Appears to be stuck in a loop.  
What do I do???

[WAWood]

@JACJ54 

It's not unusual for Windows to experience file system corruption and repair itself.  I had this happen last week, out of the blue.

But when it does that, it should only take a few minutes to do the file system check and repair and should not keep happening.  IF it takes longer and/or keeps repeating that is a sign the drive is failing and needs to be replaced.

So, let's check that first, because if it is failing, it would need to be replaced and there is no point then in doing anything else until we confirm that.

If your PC is new enough to support UEFI, you can use these steps to test the hard drive: http://support.hp.com/us-en/document/c00439024

If not, to check the drive you have to follow these steps:
1) Press Esc key repeatedly, several times a second, while rebooting the laptop. Do NOT hold the key down, just press it over and over.
2) Eventually, you will see an HP Startup Menu
3) Press the Function key for testing the hard drive (usually F2) and let it run.
If the drive checks out OK, then report that and I can provide you options for reinstalling Windows on your PC.