Q: How do I get OS X Yosemite back?

I think you need a professional to do this job

jessyy23_ wrote:

 

...But when I went to reinstall the OS (Ctrl + R in restart) it told me to try again later but I never was able to do it....

Since the Control key isn't involved in the Recovery process, it isn't entirely clear what you've tried, but if Internet Recovery (Cmd+Option+R) is available (earlier MBP's don't have it built in), give that a try if you haven't already. Note that installing Windows should change the HD's partitions enough that reformatting will likely be necessary first to go back to OS X.