Use the below at your own risk. I have not done this before. This can be used to install the plesk base packages when everything is broken
/usr/local/psa/admin/sbin/autoinstaller –select-product-id plesk –select-release-id PLESK_10_1_1 –install-component base
Or
/usr/local/psa/admin/bin/autoinstaller –select-product-id plesk –select-release-id PLESK_10_1_1 –install-component base