vave to turn firewall on after startup and get continuous trojan.gen

I don't know when, but its been for a while that my firewall is deactivated when I log back on. And my temp folder is 4+gb. During the fall Igot a bunch of trojans like 3 every minute I thought I fixed it but after I deleted my temp file that reoccurred. They are trojan.gen and trojan.gen.2  on symantec endpoint results.  They are located In the AppData/Local/Temp folder and most labe as such: dwh3cf2.dll, dwhb240.dll, etc for Trojan.Gen and dwh8a2.exe, dwhd530.exe,etc. for Trojan.Gen.2. Please help. What measures can I take to rid me of this and what to do to better protect my computer?