I believe you miss-typed one of the last commands and instead of deleting the "/etc/sudoers.d/smscon.sudoers" you deleted "/etc/sudoers" or something like that.

This is major problem. To correct it, it is too much effort and most important requires an advanced expertise level in the operating system.

Similarly to what yablacky said above, I hope you have a recent backup. After the reflash, restore the backup. If this works then you will have many things back.

I suggest you search about putty/ssh and set this up. If you would like to mess with your device it is better to do it from a real keyboard/screen.