Wireless NOT working but wired IS. DNS?

My wireless connection isnt working at times, some times it works perfect and i can connect the the internet no problem but other times i cant go online but i am still connected go the wireless router.

I need wireless as everything in my home runs off it and nothing is hard wired.

When i couldnt connect to the internet but was connected to the wireless router i unplugged the yellow LAN cable and plugged it into my laptop only to find i can connect fine but as soon as i connect it back up to the wireless router i get no internet. The wireless router is brand new as ive been having this problem for a while and i thought it was down to my wireless router being old. Virgin media say its not a problem on there side.

I did the usual diagnostics on the laptop and IIRC it says DNS server not responding.

Ive tried resetting both the moden and wireless router. Also done ip release and renew just to see if that would solve the problem but its still intermittently working. Im getting at a loose end here so any help is much appreciated

Ill be able to try some of your solutions tonight as im working untill 5.

Cheers in advance.