Burning smell from tower and then nothing else works it wont even start
Sounds like a bad power supply, also, check all the wires to see if there is any damage.
hopefull, when your PSU went belly up it didnt take your Mobo, CPU, ram and video card with it. if you have access to another PSU try it in your machine.
I would open the case, take all non-essentials right out for now. Then check the rest for burn marks of any kind and for bulging caps. See badcaps.com for that with pics of bad caps.
Try to boot.
If that fails take mobo out of case and check better for burn marks.
If you can get hold of another power supply to try and boot that would be great. YOu can boot the pc out of the case by using a screwdriver to touch the 2 pins that your power\on\off button is\was connected to.
At each point you have to check ide and all other connections, fans, etc.
If you are connected via a surge protector or UPS then plug directly into wall socket for now.
I hate to say it but this may be the time where we separate the men from the boys. You see, good quality power supplies protect the rest of the system and cheap ones dont, sometimes they go down and take other parts with them. I sincerely hope this hasnt happened to you. Im only pointing this out so that if you have to get a new power supply you will get a good one.
Either way, report back your findings.
You should also give us a bit of info as to what is in your system.