FAN Problem DEll inspiron N5040

Hi,

I bought my laptop almost 1,5 year ago and was working properly ,but 3 days ago ,it started to turn off by itself and sometime does not let me to reboot it until at least 10 min.

I went online i found out several causes that may lead  to similar problems, and mine i think is cased by Overheating.

Why: 1st- i run the diagnostic test and it passed it but had error 2000-0221 ,validation 23869.

                                                                                                      error 2000-0334  ,validation; 44073

     and the fan passed it even. with high speed 3438 RPM isnt enough to cool it i think.

   any way when the windows turns on and while it is working i noticed that the FAN is NOT WORKING at all ,why i do not know--- is it softwar/ driver problem or ?????

PLEASE  any help will be appreciatable .

                                               THank you.