I unchecked in NextSTART Preferences the 'Allow NextSTART to replace the Windows taskbar' setting.
The program is running in the background but I can´t open the Preferences window anymore to check back 'Allow NextSTART to replace the Windows taskbar.
Only the normal Windows taskbar appears.
Please how could I make the NextStart preferences window popup again.
Thanks in advance.

Multiple ways:

1. Unless you disabled it, there should be a NextSTART icon in the system tray. You can get to NextSTART Preferences from it.

2. Provided you did not change the hotkey in Preferences, pressing CTRL + F12 should open NextSTART Preferences.

3. Unless you disabled it, bumping the top left screen corner with your mouse pointer should open the main NextSTART menu. You can get to Preferences from there too (double clicking the very top edge of a NextSTART menu should also open Preferences)

4. As a last resort, kill the nextstart.exe process in Task Manager and then run nextstart.exe from the command line with the "setup" argument (e.g. nextstart.exe setup)

Multiple ways to skin a cat.

Ah, and you should also have a hotspot button on the desktop that opens the main NextSTART menu when you click on it (and from there you can get to Preferences).

Thank you so much . The second and fith options you provided worked.None of the rest, but at least you solved my problem. Very appreciated.