My Laptop(Dell Inspiron N5050) has started to blow regular sound (like a trimmer while trimming). Then I came to know that it is sound of fan then I started Diagnostic at startup by pressing F12 and after checking error code shown as
Error code 2000-0511
Msg: Fan - The processor fan has failed to respond correctly.
Plz tell me what exactly is with my laptop and how to resolve it.
It sounds like your fan is going out. You could use some canned air and while the computer is OFF blow out the heat sink grills and fan area that you can see on the bottom and/or sides of the computer. If that doesn't work you will have to get it replaced by contacting Dell if you are in warranty and having them take a look at it. If you are not under warranty then you should take it to a local shop if you have one.
First, try getting a can of air and blowing all the vents to get rid of dust. If that does not work you will need to replace the fan. You can call the Dell Spare Parts Department at 1-877-717-3355. I tried to locate a part number and did not find a processor fan. It may require you to purchase another motherboard for the system.