Dell R15/n5110 keyboard keys suddenly stopped

I have this Dell n5110
At first I began to hear some Tuc-Tuc-squeeze  sounds from inside the laptop, they were separate and occasional, but lately they appeared as 5 sounds together and the laptop sometimes hangs in rhythm with the sounds.
After that some keyboard keys stops working , at all !!
Every day more keys stops working !! now I have a few keys left.
I tried to Restart , turning power off , taking off bios battery , even reflashing the bios, still nothing seems to change.
I tried to plug in a usb keyboard and that worked fine
Do I have to replace my keyboard? would this solve it? could this issue happen again?
SOS !!!