Ubuntu was on a logical partition, housed inside an extended partition. You've deleted the logical partition, and the free space is within the extended partition. I'm not seeing a problem. Can you elaborate on what are you hoping to do with the 50GB of free space?
OK, I see now, the normal 'system' partition has been deleted, really not needed anyway on Windows 7 unless one either decides to use Bitlocker on the Ultimate version (those with a physical TPM doesn't need this), and to use the Windows Anytime Upgrade option from the Control Panel, using a key available from the Windows Store & local & online retailers to upgrade from one version of 7 to another (a Full Retail COA may be used also). The most commonly used one was from Home Premium to Pro for the many added features, including unlocking access to more than 16GB of RAM. Ultimate was good mainly for Bitlocker & language packs, otherwise didn't offer near as many features as Pro.
Otherwise, it's not needed, though as pictured, still good to keep the space free, may one day again become needed.
Great trick to free a otherwise useless partition & install a Linux OS on a freed up space anywhere else on the drive, and the waste of a Primary over 100-350MiB of space made no sense to me.
If you wish, and don't have data stored that requires that you recover the lost partitions, you may feel free to reinstall Ubuntu at any time. Should you wish to recover the partition, some of the free partition tools can do the job, yet take the advise by hollowface above seriously. Backup what you have, so that's not lost also. If you don't have a backup software installed, Macrium Reflect is the most feature filled of the free offerings, in addition to offering a WinPE bootable ISO, also offers a startup option to backup, recover or clone drives & loads very fast, much more so than a CD or USB stick ever could. The WinPE media is best used when the system won't boot, or if cloning a removed internal drive to a new one installed.