Reinstalling the package won't erase the existing config or site, only the admin console password may need to be reset.
For the CentOS system,
Code:
yum -y install --reinstall openlitespeed
For the Debian/Ubuntu system,
Code:
apt-get install --reinstall openlitespeed -y
You can back up the site config before reinstalling just in case.
Let us know if it works.