In Missouri the statute of limitations on written accounts is 10 years, however it begins to run after the last transaction. So if you used the card at all within the last 10 years the old debt remains collectible.
Depending upon the Statute of Limitations and the last time you made a payment on this account, you may have a valid defense should a case be filed in court. If however, a case has already been filed and a default judgment entered, the Statute of limitations is not as much an issue. With that said, if Discover has turned this collection over to a third party, and they are contacting you several times a day in a harassing manner, then you may be able to bring a claim under the Fair Debt Collections Practices Act. Finally, if you have several other debts that are also going to cause you trouble; you may want to consider filing for bankruptcy.
Your best bet is to consult with a local debt relief attorney who can advise you based upon both the local rules and your situation as to what is in your best interest.
You wrote, " On 5-1-2001, my husband took my Discover card & made a Cash Advance for $3,000.00. Unaware of transaction, I received a statement for that amount"
Did you dispute the charge in June of 2001?
If not, it is a bit late to complain of notice.
As attorney Goldstein wrote, consider bankruptcy or consumer law actions.