olds Delta 88 Heater problems

I have a question My husband tried to put a stereo in my car when he did my heater quit working and only has three flashing lines where the digital info is supposed to be. The stereo never worked so I took it out then the low coolant light comes on and stays on as well as the check oil light this goes off after a minute. Any Ideas what is wrong I really need a heater in my car. I have to take my 10 month grand daughter with me on errands we need heat.

Sheryl

Have you checked the fuses?

Yes I have they all seem to be good!