After logging in to Adobe ID, it shows that the serial number cannot be verified.

Hi @intelligent_Solace9223 

Please share the Windows OS version & Acrobat version you have. To get Acrobat version, Launch Acrobat and go to Help->About Acrobat Pro 

Regards

Ravi 

You should contact Adobe directly for help with this issue, using one of these channels:

Chat support: https://helpx.adobe.com/contact.html?rghtup=autoOpen
(make sure pop-ups are not blocked; type "Agent" to chat with a real person, or via phone, during working hours)

Twitter: https://twitter.com/AdobeCare

There's no email support.

Beware of people contacting you via the forums' messaging system pretending to work for Adobe! Only those with an "Adobe Employee" tag under their name are legit. Also, Adobe will never offer to contact you via Skype, or use an email account that's not under the adobe.com domain...