Are you using the Excel built in Scenario Manager?
Just a thought: what did you expect Excel to do after you had created a scenario?
Secondly, are you aware that you can select each an every scenario you create so that you can go back to your original data at any time. Or you can stay with the scenario that you prefer. In case you don't know, do this:
What if Analysis in Forecast
Under the heading Scenarios: you will see the names of the scenarios you have created, click the name of the one you want to put back into memory then click Show at the bottom ...
All of your data in your scenario model will now be changed to your newly chosen scenario!