Running engine fell

Hi, the running engine of my car fell off, the car don`t start. The recovery man said the bulbs might have been loose and fell off. The gay told me i could find someone that could just screw the running engine back in place at my house or go to a garage and ask to run a rump to make chure is that the problem.
As i don`t know anybody that could come and do the work at my house i have to go with the second option.
It looks like it is a very simply job, my question is: Is this job going to be expensive?
Will I be able to ask for the mechanic to come to my house for the job or I have to pay for a recovery vehicle to take the car to the garage?