My phone doesn't want to turn on it only shows the logo of the phone for hours and that is all I tried to unplug my phone sd card and all cards on my phone but still no fixing .
My phone is new almost a year and I recently started to use it like a month .
The model is : Samsung I5800 Galaxy 3
What I did was to install some apps and after trying to install one of them something went wrong it toke so long to install the app and after I saw no installation whatsoever at all I disconnected the installation then everything started to work very slow and nothing wanted to install or uninstall on the phone . Then I decided to turn of the phone I thought that would help the phone to work faster but after I turned it off I couldn't turn it on the only thing that do is to play the turning on music and to show the logo and that is all . And the only way I can turn it off is when I unplug the battery

What did I do wrong and how can I fix this problem is my phone dead forever or can I fix it somehow please help me I am really worried
