For common emitter configuration of a PNP transistor why is collector current 0 when emitter-collector voltage is 0? Does'nt the emitter-base voltage affect it?
Zero volts across collector and emitter can only mean zero current into the collector. It's basic ohms law.
There may indeed be base emitter current flowing but that current flows out thru the emitter (NPN) and not the collector.
If collector emitter voltage is held at zero volts and the base voltage is significant then the collector base junction is becoming forward biased and current will flow from the collector so maybe this is what you allude to?
This is the same for both NPN and PNP transistors.
I think this is the circuit you are asking about because applying an external short circuit is the only sure way to force the c-e voltage to 0 V.
In this circuit, the collector current is not necessarily 0. If the base voltage, supplied by V1, goes negative by more than a few 100 mV, then the b-c junction will be forward biased and current will flow from the collector to base, producing a positive collector current (under the passive sign convention).