It sounds like the water in the lift pipe has drained down so you'll have a bit of a job trying to pump the water up it . So long as the pump is below the water level it should eventually pump the water up . Leave that cut off valve open ,to allow air to escape , close it when bubble free water issues forth from it .
If that does not work try opening all your cold water taps , then turn the pump on , If you get water flowing again leaving the highest upstairs cold tap on till last , to try and bleed all the air out your system .
Some pump heads need a decent height of priming water first , so can you prime the lift tube via that valve being open ?
Use a funnel of sorts ( 2 liter pop bottle with the bottom cut off ?? ) & several buckets of water, then turn the pump on as you are pouring the water in , when you get pumped water coming up turn the cut off to closed .
Now the test ..... If the problem repeats itself in the morning you might have an air leak where hubby has refitted the cut off valve & the lift tube has drained down over night .
He'll need to re tighten it very carefully so as to not bust it or perhaps he'll be better off remaking the connection using new olives & inner sleeve ( it that what is already on the valve )
Another thing that has just crossed my mind . If it still drains down in the morning after working on it .
In repairing the cut off valve problem has he disturbed any joint closer to the lift tube and cause an air leak in that area as well ?