Please don't post new information within a quote box. It makes it very hard to see that you have added anything.
1. Do you currently own 20% of the shares of the corporation? Yes or no?
yes
Then you have the same rights as any shareholder of a non-publicly traded company. Please review my most recent response in this thread (post #18). What (if anything) do your corporation's by-laws say about a minority shareholder who wants to sell his/her shares?
2. What makes you think you have any right or ability "to recover [your] 20%"?
I invested 15 years of service as an officer of the company
Ok, but you didn't do that out of the goodness of your heart, right? You received compensation over the past 15 years, right?
and paid money for what I thought was part ownership of the company
And, according to you, you have part ownership of the company. You own 20% of the shares. Perhaps you were confused when you made your investment and appear still to be confused, but buying corporate shares does
not guarantee any return. Folks who buy shares of corporate stock often lose money, and sometimes they lose a
lot of money. If, at the time you bought your shares, you were under the impression that, at some unknown time in the future, you'd be entitled to recover your investment, then you were misinformed.
and took the responsibility to pay taxes for 15 years.
Pay taxes using the corporation's money? Or did you pay the taxes with your own personal funds? If the latter, why would you do that without securing an agreement for reimbursement?
My name and credit was used to secure loans and vendor credit.
That's completely standard for shareholders of small corporations and doesn't entitle you to anything. Now that you've left the company, have you notified the creditors that you are revoking your personal guarantees for any future indebtedness?