issues in PCR amplification - (Jun/02/2011 )

i am encountering this bizzare problem with my PCR reactions.... the amplified product seems to have suddenly dissappeared.. i was getting pretty good results until a few days back. i have tried with fresh components also.
can someone please help...
thanks......

is your PCR machine in order: calibrated blot?
New DNA template? Degraded template?

the machine is fine.... it was giving amplification until recently.
the template is the same as the one being used previously. so i am totally confused and have no clue as to what is happening....