ports closed after forwarding, before timed out

Hi I have a problem trying to forward ports needed for steam: my connection to internet looks like this Cisco epc3212 cable modem -> netgear wnr3500v2 ->my pc, all via ethernet cable I set up static ip for my pc and forwarded ports in router but after checking results on web port scanners it only changed from timed out to closed. I have no firewalls, neither on my pc or router, i called my isp and they told me they don't block any ports. I have windows 7. After trying dmz all my ports remain closed except for 3389 which is remote access for windows. I.ve been working on this for past few hours and i'm loosing my mind . Any ideas?

 

@TerryNet
It is definatelly a modem, netgear is getting an public ip (and my isp told me that there's no settings inside cisco, it just forwarding everything).

 

I tried with firewall enabled and it didn,t worked. Now i connected modem directly to my other pc with win xp and no firewall and got ports closed as well, but...
ive installed filezilla on this pc and i can change the port it listening on, i tried changing from 21 to various others, and when it's listening the port is open (i check listening in netstat, filezilla port is the only port being listened). Is there a way to make other ports being listened?