Hi Ivana,
Changing the password for your Method account would cause this to happen only if the Method Integration Engine is logged in with your username and password.
From the computer running your QuickBooks file and Method Integration Engine, first make sure QuickBooks is running and open to your company file. Double-click on the Method logo in the bottom-right corner of Windows, it'll be next to the date and time like in the below screenshot (you may have to click on a little up arrow to display it first). If double-clicking doesn't work, try right-clicking and then selecting Display.
The sync engine should then appear. Make sure your login credentials are up to date and click Connect to QuickBooks. Once it's connected, you should be able to resume synchronizing from the QuickBooks > Synchronize page within Method.
If you follow these steps and still aren't able to get connected, please give us a call on the Method support line at 1.888.925.6238 x.2 and we'll be happy to take a look with you.
Hope this helps.
- Justin