How to access iTunes purchases from new iMac

My previous hard drive died. Still waiting to see if they can recover anything from it. When I sign into iTunes on the new one, it does not show any of my purchases. When I look into my account information, it says: "One computer is authorized to play content purchased with this Apple ID." I can see how to edit all the other parts of the account, but not this. Does this mean I will not be able to upload all of my purchased songs even if I can retrieve them from the old hard drive?

See if this won't help you fix the problem:
How to Deauthorize iTunes on Old or Dead Computers

That's if I'm understanding your problem correctly.

No, it means you need to clear and re-authorize the computer. From any web browser, you can sign into your iTunes account go into the settings, and de-authorize all computers. From iTunes, you can then authorize the computer you're using.

If you can't recover the songs from the hard drive you can download them from the Music store again by logging into your account and going to purchases.

FYI for anyone reading this post:Don't count on re-downloading as a means of replacing missing / deleted content. Content which was available when you purchased it may not be available now due to changes in licensing agreements.

Let me start by saying I never even use iTunes, this is all of my husband's collection from over the years. I found out that the main problem was that almost all of the iTunes songs were downloaded under an old Apple ID connected to a non-existent e-mail. I had to sign in using that old account, with the e-mail long dead, to gain access to them. But in the process of signing in (or trying to) so many times, it went from saying that it was authorized on 1 computer to saying that it was authorized on 4. So learning how to de-authorize old computers will be helpful. As always you guys have saved me time fussing and getting frustrated. Thanks to you all!