Error 1720

it sounds that your were infected by virus, u cannot install that unless remove any variant on it.

The risk solution; is to remove your hard drive and connect to the other computer that has a potent antivirus.
after removing virus you take back your HDD then fixed back to original.

If this will not help, Your system was destruct by a virus so better backup your files and format and install fresh windows this fixed all errors.

If you don't want to scan the system maybe you should directly reformat it and reinstall windows.

Any problem arising thereto you can notify me for further instruction.