ID not activity

I totally understand. If it's saying it's invalid then double check your spelling. Sometimes it may be just as simple as maybe leaving out something.

If it continues saying it's invalid then you'll have to contact Apple support to have them reactivate it.

Contact - Official Apple Support

They don't have email support but you can chat Apple Support: https://getsupport.apple.com/

Then choose which Apple product or service you need help with and what issue you’re experiencing. Finally, select Chat and sign in with your Apple ID or enter your product’s serial number.

If it's saying it's not active you'll need to reach out to Apple Support: Contact - Official Apple Support