I have HTC TyTN II with Windows Mobile 6.1 and would like to update to Windows Mobile 7.5. I went to Windows Mobile site and downloaded the Zune software but nothing worked. Most of apps these days require Windows Mobile 7.5 and above.
What you have is the Windows Mobile operating system. The highest stable version Windows Mobile can be upgraded to is 6.5.3. Windows Phone is a new mobile operating system which was created to replace Windows Mobile. It cannot be upgraded to from a Windows Mobile device. You will need a new device that runs the Windows Phone OS.
It is not physically possible to upgrade your device to WP7. It doesnt have enough RAM (128MB), Screen resolution (240 x 320), or processor speed(400 MHz) to run the OS.
Even after they've spent a year optimizing the OS, You need at least 256MB, 480x800px, and 800MHz for Windows Phone.
If you want more specs about your device, you can find it here http://www.gsmarena.com/htc_tytn_ii-2024.php