This solution shows the location of the particular ic component that might get damaged when all of the above side key switches will unable to function.
Nokia 5800 Xpressmusic camera switch, slider lock,
volume up and volume down control Side key repair Solution
The slider lock switch, volume down control button switch and the camera button switch is connected with an ESD-EMI filter chip ( crystal glass IC ) marked number 1 on the picture above before it feeds to the I/O expander chip which is marked in number 2. The volume up control switch is connected directly to input and output expander chip, so there's no need to touch the ESD-EMI filter chip if only the volume up control button is not working. If all of the four side keys is not working you can then both work on the I/O expander chip. The SEND/CALL, END/CANCEL and application launcher keys were also connected on the ESD-EMI filter chip and so on the I/O expander chip. You may then check and replace both of the said IC chip if all the keys is not working or not responding.