Some power strips come with a trip switch, a small little button in one of the corners. If yours has this push it down.
This also can be a funny one - does it have a power switch
Power Cable (or 'Cab Tie' as we call it)) insulation can be very tough and you might find that those knife-edge connections are not biting all the way to the wire - as Armistead says - strip the insulation off where the connection is made on each outlet, and reinsert the wire.
If that stuff is made in china I suggest you strip it completely and rewire the insides. I've seen some really cheap, bad stuff come from there (the East). The internal wiring might be all wrong.
If you have a voltmeter handy.
On AC voltage setting, you should get these voltages across the wires
Live (Black) - Neutral (White) = 120/220 Vac
Live (Black) - Earth (Green/Bare wire] = 120/220 Vac
Neutral (White) - Earth (Green/Bare wire] = 0 Vac
If you don't get these voltages... call an electrician, as this is a mains supply problem to your abode.
DISCONNECT THE DEVICE FROM THE MAINS POWER WHEN REPAIRING !!
I say this but you don't know how many times I've been Zapped
