here's a really stupid idea that has about a 1 in a 1000 chance of working:
Email your old email address saying what you need to do. Hopefully, the person who owns the account sees it, and is nice enough to access the email from toonslab support to change the account's identification email and change it to yours.
now this completely ridiculous idea is completely banking on these factors: that the person sees your email; is nice enough to access the email sent by toonslab and go through the
process to change the account's email to yours; and if toonslab will reply at all.
if this idea which in all likelyhood shouldn't work doesn't work, you're out of options. start the grind again.