Okay, so I wanted to decrease the Ubuntu partition from 128GB to 64GB. Windows wouldn't let me do that. So I figured I'd delete the 128GB partition and create 64GB and reinstall Ubuntu. But after I restarted. Now I'm getting "error: Unknown filesystem. Entering rescue mode..." I don't have access to another computer accept my Windows Phone.
First of all, do not freak out. Your Windows partition (and your data) is not affected. By deleting the Ubuntu partition the BootManager that took care of the dual boot to Ubuntu and Windows was also deleted.
You could use an Ubuntu Live CD/DVD to reboot from. One of the installation steps will let you allocate only 64 GiB out of the 124 GiB remaining unallocated. At another step it will setup the BootManager to allow you to dual boot.
Another way, is to use a Windows DVD to fix the BOOTMGR. Steps are presented in this article http://pcsupport.about.com/od/findbyerrormessage/a/bootmgr-is-missing.htm