2004 Hyundai Santa Fe

I just had the timing belt replaced full tune up and water pump. My wife drove it home the day after the repairs and maintenance. She turned it off in our drive way without incident. Later that night she started it to move it and it immediately started to knock alot it is a constant knock a mechanic looked at it and said the oil pump wasnt pumping. Will the oil pump not working cause4 this noise will it go away once the new oil pump is installed? Is the oil pump driven by a belt. Is there anything the mechanic that worked on the car could have done to cause this failure to happen. Thanks any help will be appreciated I have to give my wife a ride to work. Hopefully a miracle will happen and I wont have to argue with her on a daily basis as far as my driving ability's are concerned.