MAC drive type error , reverting back to hfs+

hi guys,

I'm a new mac user , so excuse my lack of knowledge about this operating system.
i recently installed windows 7 on my imac, (previously mac os 10.8) after download,
from withing windows 7 disk management utility, i accidentally shrink the drives to dynamic type.
and now the problem is i don't know how to revert back to previous type, As i cant run mac os

thanks in advance , any help would be appreciated , :)
Did you use the Boot Camp Assistant in OS X to install Windows 7?
If that was done correctly, then you just need to boot back in the Mac OS X system.
Restart while holding the Option/Alt key.
That boots to the iMac "Boot manager" screen.
Choose the OS X boot (probably still named Macintosh HD, unless you changed it), and press enter to boot to that system.

If you did not use the Boot Camp Assistant to install Windows 7, but you REPLACED the original Mac system with Windows, then that won't work.

If that's what you did when installing Windows, try booting to the original Recovery Partition:
Restart again, while holding Command and R (if it is not clear, the Command key is immediately to the left of the spacebar.)
That should boot to a Mac menu screen, showing 5 choices, including Reinstall OS X, and Disk Utility.
If you have used Windows to change the format of the hard drive to NTFS (which is the default format for a Windows partition), then you will need to use the Disk Utility to change the partition format back to MacOS Extended, which will erase everything. After changing the partition format, Quit Disk Utility - which will return you to the main menu. Continue on with the choice to Reinstall OS X.
Thanks ,
Had to use mac recovery partition to re-partition and format hard drive ,then re-install mac Os
works great now.

But, Still wondering if their is any disk utility for windows to change the format type back to
HFS+ , there have to be a way because i just lost all my data from previous Mac Os :(

Anyway , thanks a lot for help :)
Here's what happened (although I don't know for sure): You allowed Windows to install on the wrong partition, replacing the OS X software (and all the Mac apps, etc.)
The problem, as you now know, is that you let Windows erase your hard drive.
That's why it's a good plan to follow the instructions carefullywhen installing Windows, and use only Apple's Boot Camp Assistant to make the partition for installing Windows, then be sure that partition that you create in Boot Camp is the one that Windows installs to. Otherwise, you will continue to have the same problem if you try to install Windows again.

To answer your question more directly: If you allow Windows to change the partition format on the wrong partition, then the data on that partition is gone, and not recoverable (without some recovery software, and probably not even then). Your only choice is what you did, which is reinstall from the recovery partition, which, as you know, is simply a new install.
You always must be careful when formatting a partition, that you are choosing the correct partition, and that you know you will be completely erasing that partition.