Help with my H-bridge circuit using MOSFET
That's really very simple. You have connected your p-type MOSFETs backwards. 

Do you see the diode symbol which is part of the FET? Notice how it points downwards? There is in fact an effective diode, called a body diode, which results from the construction of the FET, and it behaves just like any other diode. As you have connected it, current will always flow through the diode, and the FET will behave as if it is always on.

Reverse the source and drain on the two IRF9630s, and try again.

Also, for what it's worth, you do not need Darlingtons as gate drivers for the p-types. Regular old NPN BJTs will work just fine.

However, at 32 volt power supply, you really should switch the 5k and 10k resistors on the p-type gates. In theory, these will provide 20 volt gate drive, and the FETs have a maximum gate drive of 20 volts. This means that you have no margin, and risk overdriving your gates. Replace the 5k with a 10k. This will give you a nominal 16 volt gate drive, which will be entirely adequate and does not flirt with disaster.