Yea NEVER EVER use the clean command unless you plan to wipe the whole disk.
and it sounds like you booted the DVD as a Legacy Boot. To install ANYTHING as a uEFI boot which requires GPT when you boot from a device it should list as uEFI Boot DVD Drive or something like that. You want that. Once you do that it will load and install on a GPT Disk.
I can walk you though a few things but you need a Thumb drive and another PC to download some software and burn to the USB drive.
Notice: You are doing this at your own RISK. I can not be held accountable for any possible data loss.
First thing is download Rufus from here
http://ttztools.homeip.net/ISO%20to%20USB%20Tools/
Now download the testdisk file from here
http://ttztools.homeip.net/Partition%20Recovery/
Now open up Rufus. Select at the top the USB drive you wish to use. Leave everything else alone.
Then go down where it says Create a Bootable Disk using - Make sure FreeDOS is selected. Now click start. Now take the Testdisk file and extract the files directly to the same thumb drive. it should have a folder caled LOCALE and then all the files from the test disk.
Now boot off of that.
Once you start it it will just give you a C:\
Type in Testdisk and then press enter
Test disk will start up. it will ask about logs and just hit enter.
Then it will list your disk. select your disk and press enter (Will say something like 500 GB / and then a GB number in free space)
Now select it and press enter.
Next screen shows what partition table it was. Now we need to select EFI GPT since that is what the disk was and press enter
now select analyse and enter and then enter again as quick search is selected at the bottom.
Now the next part will take some time.
Once it is done it should fine the partitions. At this point here is when you could overwrite anything that might be on there. So press enter and then press enter again. Then the next screen at the bottom it has the option to write. use the arrows to select write and then press enter and then Y to confirm.
If it DIDN"T find all the partitions that were on their before do NOT write it! Select the Deeper Scan and see if it finds it on that scan.
If it doesn't find the all the partitions then we will have to try other software. DO NO WRITE unless you are SURE it has found ALL the partitions!
if it finds them all, and you click write, you should be able to just hit CTRL+ALT+DELETE and restart and it SHOULD boot up as it once was.
then we can move forward on how to properly dual boot.