I had a problem with my RasPi and it couldn't boot to lxde. So I tried fsck /dev/mmcblk0p2 and it works again. However, my Apache cannot start anymore so I can't open localhost and phpmyadmin. The error is "cannot load /usr/lib/apache2/modules/mod_auth_basic.so". Do you have any idea how to fix it?
How did you do fsck? If you did it while system running (that means /dev/mmcblk0p2 mounted as /) you did it wrong. Linux filesystems should not be check/repair while mounted.
If you did check/repair filesystem while mounted maybe apache modules moved to /lost+found folder which is a linux special folder. You can search your file in /lost+found then move to original folder if you can find it. I suggest you backup your SD card, re-image with your system then restore your files.
From fsck manual :
Note that in general it is not safe to run e2fsck on mounted filesystems. The only exception is if the -n option is specified, and -c, -l, or -L options are not specified. However, even if it is safe to do so, the results printed by e2fsck are not valid if the filesystem is mounted. If e2fsck asks whether or not you should check a filesystem which is mounted, the only correct answer is ''no''. Only experts who really know what they are doing should consider answering this question in any other way.