Any fix for a schrader valve that won't open? I have the all too familiar problem of being unable to pump up my tyre :(

It's not a problem with the pump (because it works on the other wheel) so I guess there must be something wrong with the schrader valve. I've done all wiggly woggly poking efforts to get it to release air, tightening, untightening the pump head etc. to no avail (I just keep pressurising the pump instead of the tyre). However the valve doesn't "look" damaged (the pin is in place, straight, not obviously damaged).

Is there any other possible fix to this that I haven't tried? Some clever tip or trick? Or should I just give it up and buy a new inner tyre?
Sounds like the valve has stuck shut, this can happen if the rubber seal at the base of the valve swells up. If the valve core is replaceable just get the appropriate valve tool and a replacement core,  both are really cheap. 

Otherwise its likely to require a replacement tube.