Which windows version

CheckDisk or ChkDsk can be run easiest for you maybe by right clicking your c drive and selecting properties.. then you probably see a tab for tools. Click top item in the check disk for errors box that pops up runs ChkDsk at next restart of your computer.

Scans files for improper dates and other simple things. Fast scan ..... the bottom box in that check disk for errors box is a more complete scan .. checks the whole hard drive for errors.

Check both boxes and do the reboot as Mikie reports. On the boot up a DOS screen will appear and offer an opportunity to abhort the activity. Take no action. The multi-step process will start on its own. In most cases it takes quite a while, and your system will not be useable so be patient.

This is perhaps a habit from the old days, but I recommend to users to do a Disk Cleanup, or better yet a cleanup with CCleaner before utilizing Checkdisk.

DA

Chkdsk

you might consider backing up your important files and data if you are suddenly getting a chkdsk message. It could possibly be a warning of impending hard drive problems.
At any rate you should be backing up your files and data regularly for safety. Or you can use an imaging program and create an image of the hard drive. There are several free ones.
EaseUS Todo Backup Free
Macrium Reflect
those are a couple of free ones.