Hi, so i recently fixed the problem that you were struggling with(and I for a while). When you tried Davids cmd, I did that too. It removed the searchapp. If the search app is removed, you can't enable or disable search because none of those things will work if there's no search.
Solution: 1
press Win+R
type cmd and press Ctrl+Shift+Enter
It should be in the administrator cmd prompt.
Type sfc /scannow
wait till its done and once it is, check if it says Windows Resource Protection found corrupted files and successfully repaired them. If it does, exit out of cmd prompt and see if search works.
Solution 2
If it does not work, try going into task manager and services. Then open services scroll down to windows search and click enabled if its disabled already.
Solution 3
If that does not work try to rebuild the search index by going into indexing options and pressing the button called rebuild.
Once its done rebuilding, your problem should be fixed.
Solution 4
If that does not work, I would suggest to restore windows 10 to a previous point.
Right click the search bar and open task manager. Then click file and run a new task. Type Control Panel and press enter. Go to recovery and click open system restore. Click next, and choose a date that you want to restore to. Then, the next is pretty self-explanatory. Your PC will start to rebuild to match up to the restore date. It may take a few hours or if you don't have many applications or if your PC is new, it will finish in a couple of minutes. You can step away from your computer because it will restart when its done by itself. After system restore is done, try to log in. If it works then its a success! Sorry if my English is bad. If you can't understand something clearly just reply.