Are you sure that you have posted the code that you are using ?
It won't Auto Format - "Too many left curly braces". Final brace missing from the loop() function
Fix that and it won't compile - no semi colon on the digitalWrite line and no brackets round the if condition
You're not using the internal pullup resistor, so your switch wiring is more complicated than it needs to be. How IS your switch wired?
Have you looked at the blink without delay example? You don't need TimerOne at all. When the switch is pressed, record when that happened, and turn the LED on. Periodically, if the LED is on, see if it is time to turn it off (now minus then greater than or equal on time). If it is, turn the LED off.
"it" is, that the attached interrupt routine doesn't turn off the led after 1 sec as it should do - imho. and i used the code-tags?!
@pauls:
the switch itself is working. it turns the led on, but the ISR doesn't turn it off.. that is my problem. and yes, i've looked at the "blink without delay" example, but i need an interrupt because there is supposed to be code executed while the timer is counting. i use this example to get this interrupt stuff working before messing up the bigger project, where i want to use this.