Is the PS2 actually running, when you switch the power on at the back, does the red light come on at the reset button? If not you have either a proble with power getting into your PS2, or theres a problem inside the PS2 maybe a bad connection. If the light does come on, when you press the reset button, does the light go green and do you hear the PS2 start up?
Other things to check, are you selecting the correct AV channel on your TV, if yor TV has more than one scart socket then your PS2 may not be on AV1, try the others. Are you actualyl selecting the AV channel? If your hearing the PS2 start up, check it on a different TV, try using a different scart lead from the PS2 to the TV as well, use a friends. If none of that works then the problem is in the PS2 and you need to get it looked at.