Modern televisions like the Panasonic Viera can experience any number of technical issues that all require their own unique approach to troubleshooting. Standby or powersave mode is a feature built into TVs and other electronic appliances that indicates that the TV is not powered on. If you find your TV in standby mode, take a few simple troubleshooting steps before having the TV serviced or purchasing a new TV--steps that can be easily applied to the Panasonic Viera or any other make and model of TV.
Power the TV on by pressing the power button on the remote control. As noted, standby mode is essentially the same thing as the TV being completely off, so the first step in troubleshooting is to attempt to power the TV on from the remote.
Try powering the TV on from the front panel power button to test for a problem with the remote control. If your TV powers on from the front panel but not from the remote, you may need to replace the batteries in the remote or replace the remote altogether. If your TV stays in standby mode whether powering it on from the remote or the TV, some further troubleshooting is required.
Unplug the TV's power cord from the electrical socket or surge protector into which it is plugged. This is know as a "power cycle" and can often resolve minor technical problems that the TV experiences. After 30 seconds, plug the power cord back in and try to power the TV on from standby mode. If the TV still will not come out of standby mode, the only remaining option is to have the TV serviced or to contact Panasonic technical support.