My cpu fan speed too high how to control it?

s of two days ago the CPU fan is running too fast and VERY loud. I removed the fan and blew the dust out of the cooling fins. When the problem didn't resolve I removed the heat sink and found no dust behind it. Put it all back together and it still runs very loud. There was also some type of sealant between the CPU and the heat sink. I don't know what it was and what I should use in place of it. I also don't know if the sealant would make any difference. I have a Pavillion et running Windows7. Would appreciate any help. I am semi skilled but do not own any diagnostic tools and obviously I can't afford to simply order a part on a trial and error basis. I tried to see if I could get a new fan from HP but it is listed as available only from reseller. I don't know what that means as I bought the unit from HP so there is essentially no reseller. HELP please.