Go to Control Panel, Add/Remove Programs.
Click on Add/Remove Components.
Click on Accessories and Utilities, Details. A new window will pop
up. Click on Accessories, Details.
When the new window pops up, check that all the boxes are ticked.
This checking ensures that you didn't accidentally uninstalled
System Tools programs.
If all the boxes are ticked, try searching for them here:
Backup: C:\Windows\system32\ntbackup
Character Map: C:\Windows\system32\charmap
Disk Cleanup: C:\Windows\system32\cleanmgr
Disk Defragmenter: C:\Windows\system32\dfrgntfs