Sounds like your alternator is not charging properly, but let's get the jacks up.
It sounds like the 100 amp DC breaker from your house batteries is tripped (or your house batteries are dead).
The breaker should be close to the house batteries and looks like:
Push the button to trip it and push the flag back in to reset it.
This breaker also powers your generator so if you can crank your generator then this (and your house batteries status) is not the problem.
If you have reset the panel and are running the engine so there is > 12.7 VDC sensed by the panel the "Low Voltage" light should not be lit.
If the generator cranks and your low voltage light is out and you still can't retract the jacks you may have an issue with the hydraulic pump or it's solenoid. In that case break out your Lippert manual for the manual procedure to retract the jacks (or download the manual online). This involves opening solenoid operated hydraulic valves with an Allen wrench and spinning the motor/hydraulic pump with a socket (and ratchet or drill).