I unlinked a credit card account. It no longer shows in the banking area and thus downloaded charges don't show. How do I find them/categorize them?

It's great to see you here in the Community. @richard-rhodeswo. I'm here to clarify and give you the information you need to resolve your concern.
 

The downloaded transactions that were uncategorized will be removed as soon as you disconnect the bank from the Banking page. While categorized transactions will no longer appear in the Reviewed or Categorized section in the Banking, they will now appear directly in the Chart of accounts.
 

If the missing transactions are not in the Chart of Accounts after disconnecting the bank on the Banking page, they weren't categorized. So if you want them to be categorized, you'll need to manually enter transactions or reconnect the bank in the Banking page and categorize them manually.
 

Once you reconnect your bank on the Banking page, the only transactions that will be downloaded are those from 90 days ago, including the ones that were already categorized. 
 

To avoid duplicate transactions on your register, you'll need to exclude them. The transaction moves to the Excluded tab of the Banking page.
 

Here's how to Exclude:
 

1. Go to the Banking menu, then select the Banking tab.
2. Click the For Review tab.
3. Tap the checkbox of the transactions you want to exclude.
4. Then Exclude.
    

You might want to create rules that automatically categorize transactions for you. Here's an article for that: Create a bank rule. 
 

If you want to reconcile your account in the future, you can check out this article: Reconcile an account in QuickBooks Online.

Don't hesitate to post a reply if you have any clarifications or additional information on your banking transaction. I'll be around. Take excellent care of yourself!