Once you've performed any necessary backups, run through these steps to get Search working again. 

  1. Hit the Windows Key + R shortcut on your keyboard.
  2. Type regedit and hit Enter on your keyboard.
  3. Double-click HKEY_CURRENT_USER.
  4. Double-click SOFTWARE.
  5. Double-click Microsoft.
  6. Double-click Windows.
  7. Double-click CurrentVersion.
  8. Double-click Search.
  9. Right-click the right pane of the RegEdit window to bring up the menu.
  10. Click New.
  11. Click D-WORD (32-bit) Value.
  12. Type BingSearchEnabled and hit Enter on your keyboard.
  13. Double-click the BingSearchEnabled entry you just created.
  14. Type 0 in the Value data field. (It should already be 0 but make sure).
  15. Click OK.
  16. Double-click CortanaConsent.
  17. Type 0 in the data field. (It should also already be 0 but make sure).
  18. Click OK.
  19. Restart your PC.

This should bring Windows 10 Search back online.