I am sony ericsson j105i naite user. Front camera is not working in my phone. when i starts front camera then show only black colour on phone screen. So please give me some guidance to solve this problem.

Seems your fault can be related to a hardware issue in the mother board but just to take a possible solution to reset if the phone has hung up because there of errors in the software. So to reset remove the battery and the memory card from the phone. Using your PC , scan the memory card for any corrupt files or media files with virus- it is possible when they are downloaded from unsafe sites. If so remove or format the card. Now replace the card and battery and switch on the phone. If the phone hangs up then it is confirmed that the software is corrupt and will need a reinstallation. Seeking help from the authorized service /support centre is most ideal. Take estimate and decide.

Inactive sim problem