I own a Nikon D90.
I am new to exposure setting. In Manual mode, I could see the exposure meter changing towards right of zero and towards left of zero informing about under exposure and over exposure. I clicked a few photographs as well. However, I do not know what happed, I now see that the exposure meter doesn't change in Manual mode. It seems to be stuck, i.e there is a bar that appears to the right of zero. It doesn't change, not matter where I focus. I initially thought it could be problem of the camera, so I switched to P mode and it was working fine there. I remember having used the Exposure Lock buttons AE-L/AE-F button and the focus lock switch. I tried to change their setting as well, but the meter reading doesn't change. I tried to do the following but none of this helped me fix this problem.
1) Reset the camera by pressing two green buttons at the top.
2) Removed the battery and inserted again.
This camera is just 2 months old. Could someone help me in understanding what has gone wrong. Why the meter reading is not changing in Manual mode?
Following is the various setting I am using to capture picture
Af-area mode to Single point
Based on the advice given here, I detached and reattached the camera. After doing this, I can see the Meter scale only for "S" and "M" mode in the Viewfinder