Computer issues
 

So I have a 2002 MC 3.4Ls and all my problems started when my car keys were stollen. After about 3months without car keys I finally decided to replace the ignition lock and ignition housing cylinder. After I had the parts replaced I now had a new set of keys and a car that would not start the damn thing wouldn't even crank. So obviously I was worried and for good reason because I realized how bad I messed up, turns out I think I need a OBDII code reader to reprogram the car but I'm still not sure if that will work and i can't seem to get my hands on one. Also I think my BCM has went bad because my dome light and rear view mirror lights flash on and off while the dash lights up and makes a weird clicking noise. I also think my PCM is going bad as well because before my keys were stollen the fan would turn off even while the engine was getting to hot. I'm young and this is my first car and I absolutely need help so will someone PLEASE help me out!!!!

Start with one thing at a time. Make sure the battery is fully charged before going forward. First, if it's not, the computers in these cars can and well do weird things (I used to have a parasitic drain on mine and it would kill the battery in 3-4 days of no driving, a lot of times when that happened, the back up lights would flash).

The key, if you have valid proof of ownership, a new car dealer can use your VIN to cut a new key for the car, matching the original. May be handy to have for the trunk and doors.

When you change the lock cylinder, you do need to perform a "relearn". This can be done with a GM Tech II or there is a non-GM Tech II method. Follow the PCM relearn instructions, they are the same process. Works perfectly, but make SURE you have a fully charged battery. Here is the link to the relearn:
https://montecarloforum.com/forum/fw...rocedure-8598/

Thanks for answering my tough Q
 

Well that was my mentality at first to just take my time and figure things out, but the first thing I did was replace the battery because my old one was garbage,next I decided to take my starter and my alternator to the nearest auto part store for testing and to my surprise my starter and alternator were working fine. Now my starter has not been plugged in correctly and that's why I believe the relearn procedure hasn't worked, So I guess now I need to know what I should do with my options being.
1.Pay out my ass and go to the dealership
2.Try to get a OBDII code reader and see if that can help
3.Plug my starter in correctly and pray the relearn procedure will work
4.Replace my BCM and PCM and have the dealership program everything together
Hopefully these are not my only options, any suggestions

Go with the cheapest method that may work first.

Plug starter in correctly and perform the re learn process, if after that has failed then starting sourcing other options.