Back up what you can right now and get a new disk!
Why? Because your disk has got irreversibly damaged regions that are no longer writeable or even readable.
The OS usually marks such bad sectors and stops using them. However, once a disk starts to get them, it's likely that there will appear more damaged regions in the near future,
To get more information about your disk, you can check its SMART status and run some self-tests. You get there by selecting "SMART data & self tests" in the hamburger menu in the top right corner, or by pressing Ctrl+S.
Your hard drive is failing.
Make a backup ASAP and buy a new hard drive.
First things first:
Back up what you can right now and get a new disk!
Why? Because your disk has got irreversibly damaged regions that are no longer writeable or even readable.
The OS usually marks such bad sectors and stops using them. However, once a disk starts to get them, it's likely that there will appear more damaged regions in the near future,
To get more information about your disk, you can check its SMART status and run some self-tests. You get there by selecting "SMART data & self tests" in the hamburger menu in the top right corner, or by pressing Ctrl+S.