Based on the information you provided it appears the IRS froze and then changed your tax return. The letters are indicating that you do owe money and that a refund was not the result after their review.
Once you receive the transcript you can compare this to the return you filed to find, to check the differences. If you are unsure of how to proceed you should seek a tax professional for assistance. It may be a good idea to do this before your file your return for this year so you don't have a similar situation.
Based on the information you provided it appears the IRS froze and then changed your tax return. The letters are indicating that you do owe money and that a refund was not the result after their review.
Once you receive the transcript you can compare this to the return you filed to find, to check the differences. If you are unsure of how to proceed you should seek a tax professional for assistance. It may be a good idea to do this before your file your return for this year so you don't have a similar situation.