I formated my windows partition on mac. I want to merge them but i can't.

--- Post Merged, Feb 3, 2016 ---

128gb not considered large enough for Windows as well.

Perhaps of help,

< http://www.cnet.com/how-to/how-to-delete-a-hard-drive-partition-on-a-mac/ >

 

The correct method to retrieve the space from a boot camp partition - is to run the Boot Camp Assistant, which will give you the choice to remove the boot camp partition (and merging that space back to your OS X partition.
HOWEVER, if you have done other mods to your hard drive, like adding more partitions, or using something other than Boot Camp Assistant to modify your partitions (such as Disk Utility), then you don't have many options.
And - maybe your only option to retrieve all your space - you should erase your hard drive (which will remove all existing partitions, including your OS X partition. That will take you back to the single partition that you want. It ALSO removes anything that you don't already have backed up, such as pictures, music, personal documents, your applications that you have added to your OS X system, etc.
If you are OK with that, either with a full backup, or you don't care , then go ahead with a full erase.

And, then reinstall OS X. That will give you a fresh install, and all your space will now be available for your use...

 

I Agree with DeltaMac, that it should have been done in Boot Camp Assitant. If that is not longer possible and Disk Utility will not do it. I would try to boot (cmd+r) into recovery and try Disk Utility from there.

 

FWIW, if anyone needs to resize their BootCamp partition - CampTune is the solution.

https://www.paragon-software.com/home/camptune/

Also, BootCamp backup...

https://www.paragon-software.com/home/bootcamp-backup/

 

I had a similar issue recently. Have you tried using the command line diskutil? Start with opening terminal, typing in "diskutil list". You'll get something like

Code:

diskutil list
/dev/disk0 (internal, physical):
  #:  TYPE NAME  SIZE  IDENTIFIER
  0:  GUID_partition_scheme  *512.1 GB  disk0
  1:  EFI EFI  209.7 MB  disk0s1
  2:  Apple_HFS Macintosh SSD  511.3 GB  disk0s2
  3:  Apple_Boot Recovery HD  650.0 MB  disk0s3

In your case hopefully you have free space after your osx partition. Then try "diskutil resizeVolume /dev/disk0s2 R", substituting disk0s2 with the disk corresponding with your osx partition. The "R" at the end just means resize it to the maximum size possible. Diskutil will first run a verify/repair on the partition. If that fails, you will need to repair it by booting to the recovery partition, and doing it there. Once it is repaired, try the command again (you could run it from the recovery partition, wont matter). At least with the command line you get a bit more feedback and verbose error reporting than the disk utility gui.