Finally, I got my PC recovered. I went to the market after having no solution to it. They told me that it's the BIOS issue. They furthermore asked me to do the BIOS, I let them do so. But it didn't helped me out. I visited another repairer, he analyzed that the some of processor chip pins are damaged. He replaced the motherboard with new one along with extra 4000 Pakistani Rupees (1usd = 210pkr at that time).  In my case it was the board's issue but you can have a BIOS issue with 90% chances. 
I have a Dell Optiplex 790 tower that will not post. I get a 1-3-2 beep along with the #1 light lit up. According to the Dell website, this means that there are "No memory modules are detected". I already tried reseating the ram, tried all four slots and every combination possible of those four slots. I tried taking one ram stick out and only having one in, then tried with just the other ram stick in and I get the same beep codes with just one and just the other. I also tried clearing the PC of any residual power, tried clearing the CMOS, I also tried wiggling the heat sink, pretty much everything that I could come across scouring the internet. Same beep codes I also tried using a can of compressed air to remove any dust that may be in there, and I shined a flash light in there and the slots are clean as can be. Same beep codes I am at a loss here, the PC worked two weeks ago so I have no clue what the problem could be. I doubt both ram sticks would go bad at the same time—especially when it worked two weeks ago. The light on the back is solid green. Is there any other things I can do to fix this?
Beep Code 1 3 2 on Dell Optiplex 790