I need to prepare all journal entries to correct the above closing entries

Fees Earned Dr 15000
Accumulated, Amort Dr 5000
Interest Rev Dr 1000
Income Summary Cr 21000

Income summary Dr 19000
Salaries Exp Cr 12000
Prepaid Advertising Cr 5000
Interest Payable Cr 1200
Office Supplies Exp Cr 800

Capital Dr 2000
Income Summary Cr 2000

Withdrawals Dr 6000
Capital Cr 6000

I have figured out all the errors, (accumulated Amort, Perpaid ad and Interest Payable) but now I have to prepare correcting journal entries and I am not sure what they are asking me to do.

To correct something that shouldn't be there, you have to reverse it out. Since amortization shouldn't be there, that debit should never have happened. So you credit it to un-do it. And likewise debit the Income Summary for the same amount since that shouldn't have been part of the total.

Etc.

You will then have to correct the closing of income summary because that balance will change. (I don't know where this all came from or if you have a trial balance, but leaving you with two expenses just seems weird. If there's a list of accounts somewhere, you also need to see that nothing was missed as well.)

And the drawing closing is backwards. Withdrawals are already a debit, so debiting it again will only double it, not close it.