Can someone please give me some advice on electrical problems?

Out of nowhere my speedometer froze up, well atleast the miles and trip, they just froze n stopped working, then a day later my air condition stopped working, that and the heater, the blower wont kick on, and then a day or 2 after that my stereo system started shorting out, it will play then get alittle staticy then the music will only come out 1 speaker and it will be really low reguardless of the volume and kick back on then right back off or really low in 1 speaker, someone said it might be a bad ground or a bad cluster, its a 98 ford mustang, and I need to get it fixed asap so if someone knows what it could be or some ideas id appreciate it greatly thanks