no siren sound anymore

I just installed a CompuStar Pro P1WSH-A alarm into my 1994 Integra. It was working fine for a few weeks now until my car couldn't start and had to tow it to the garage and then they replaced my spark plugs. After that, the siren doesn't work. What seems to be the problem? How should I go about testing if it's the siren that's broken or it's the alarm's fault?

They probably cut the wires going to the siren when it was at the garage.  They seem to do that when they can not get the alarm to quit sounding.  Find the siren and follow the wires, check the ground wire also.

Is there a L.E.D. installed...Could be in Valet Mode...Is the L.E.D. on solid...?M.E.C.P & First-Class

Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!

first as tommy said verify it's not in valet mode, if it isn't then to test, at the siren ground the black lead of your meter, and probe the red wire for voltage while you arm/disarm the alarm, if you have voltage, check your ground, if they're all good you have a defective siren, if you have no voltage on the red wire, then you wil have to check at the control module for voltage, if you have voltage at the control module, your wire is broken somewhere, if not, then the output on the unit is defective.commit your way to jehovah and he will act in your behalf. psalms 37:5