Unable to play song bought in another country (transfer account to new country)

Several years back my iTunes account was an USA account. About 4 years ago I transferred it over to my new home country of Canada. I'm noticing that I'm unable to play any songs that were purchased during the era it was a US store account. I legitimately purchased these songs but I get the pop up message ''This computer is not authorized to play <this song> would you like to authorise it? (I'm entering my account info but to no avail (my Apple ID /email address has NEVER changed in all the years I've had an account)

Any way to get these songs back - I'm beginning to realize just how many songs I'm missing and how many hundreds of $$ it would cost me to re-purchase?