Lost all my bought apps and music

So, I just installed Windows on a new SSD. I installed iTunes to install one more app on my iPad, when it started nagging that it wanted to delete all content on it. I told iTunes to not do that, and I started trying out syncing without deleteing everything. At one point iTunes told me it needed to authorize my computer to transfer purchases from the iPad, I tried it repeatedly and it just failed with some "server timeout" or similar error.

I cancelled that process, and authorized manually through the menus, then I tried looking for the option to transfer the purchases again, I couldn't find it, so I disconnected and reconnected the iPad, and continued doing other stuff on the computer while it was doing all the detection etc. ... a few minutes later when I look at iTunes the next time, I notice it's busy deleting all my content.

Now I lost all the apps and music I bought and downloaded for that iPad AND my iPod touch, eventhough I used the same iTunes library folder

and I went to the settings and changed the iTunes library to be the same folder as it was on the previous Windows installation. I tried to re-download by choosing Check for available downloads from the menu, but it just tells me all my purchases have been downloaded.