I have tried to login to Skype.com and my app on my Windows Phone (7.5) but either my Skype name isn't working or I forgot my Skype name. Either way, I tried to find out my Skype name with the temporary code, but it never worked on my computer or my phone. What should be done to fix this?
It seems that you have created a Skype name by logging in with a Microsoft account on another platform, in this case you need to use the Microsoft account to log in. On Skype.com sign-in page you need to choose the option to log in with a Microsoft account. On Windows Phone 7.5 there is no option to sign in with a Microsoft account, only Skype account.
To log in on Windows Phone 7.5 you need to unlink your current Microsoft account, create a new Skype account and then link your Microsoft account to the existing Skype account you created. In this case you can use the Skype username to log in on your WP, however, you will in this case not see your Messenger contacts on the WP.