How to revive my windows 10 after installing ubuntu?

I have 3 hard disk drives, 500 G blue, 1Tgreen, 1T blue cavier!
I have installed a windows 7 on my 500Gig HDD. and recently (actually couple of months ago)
I installed windows 10 64bit on my newly purchased 1T blue cavier hdd.
again after sometime, I needed to install ubuntu. so I split my last partition from the 1T blue cavier hdd and installed the OS. and my windows 10 boot is gone.
I tried to fix it, I got the windows 10 working and the linux boot was gone! after sometime, I got the ubuntu and windows7 ok, and now the windows 10 is gone!.
What should I do now, I both need all of these Oses and I have no idea how to make this work.