why cant i masturbate again for about another hour after i have already done it !

This is normal. After you have climaxed, it takes a time to regain. If the sex desire is very high, you may be able to recover fast.
When I had first sex with my girlfriend, I was really nervous. After climax we both kissed and parted. I went to home and started thinking what I did just a couple of minutes back. Thinking about those steamy moments, I got a hard on and ended up doing masturbation in less than 45 minutes.
It all depends on how strong your emotions are.

Seeing as you are trying to masturbate this much in a short period of time, it seems as if you get really bored easily. Try to find activities to do that will keep you busy, as even though masturbate a few times a day is very healthy, masturbating multiple times in a single hour isn't very healthy. I suggest as I said before doing something else instead, or just wait the hour, as that's very normal.

Some men can and some can't is the best answer I can give you but IMO it's mostly genetic. Some guys can stay hard after they come and keep going until they come again. Other guys will go soft for a period of time, anywhere from 5 min to 30 min and then get hard again. Everybody is just different. If you want to bad enough just keep trying.

generally that's because after you comed your penis exerted all the semen and needs time to create more.
However, in your case your just perverted so screw yourself in an hour.

When God was creating humans, men chose the option to Pee standing up and women chose multiple orgasms. We chose wrong.

stuff has to build back up