How do I find out the iPhone4 has 8G, 16G or 32G

paul Tang, this would depend on what your iPhone is doing. If you can still get in the menu, go to Setting>General>About this is where you can check the capacity of your phone. If you can not, you may have to open your phone, and take a look at the memory chip. This teardown shows you the location of the chip. Google the Samsung number for the flash memory and you will know what phone you got.

AS for not working, it would be important to know what it does and does not do. Check for any obvious damage, like missing components on the logic board, corrosion etc. Then you could got ahead with a good isopropyl alcohol cleaning. After that, try and plug it into a wall AC charger, since the battery may be to discharged to be charged from a USB port. If you have no luck with that, change the dock connector and the battery, reevaluate after that. Oh and by the way, you also want to start off with a hard reset:" Hold the sleep/wake button and the home button at the same time. Hold until you see the screen go black. In some cases, you may need to keep holding even after the red power off slider appears. If it does, just keep holding it. Once the white Apple logo appears, you can let go. The iPhone is now rebooting. Hope this gets you started. Good Luck.