if you have one switch then the best thing you could do is to register how long the button is press.
depending on how you set up your hardware the simplest implementation would be to detect the change/transition of state of the switch. recond the time between press and release then you have something to work with
say maybe something in line with this will help
if PreviousSwitch low and CurrentSwitch high record time means the beginning of press
if previousswitch high and currentSwitch low record time means switch release time
then use if release-press>=2000UL then led blink 2second else led blink 1 second.
HTH...