Question mark folder after reboot and cannot detect other boot option!
just to update.

the hard disk actually crashed!!!

omg, can't believe that actually happened.

and the guys at the service center told me my data was unrecoverable...

guess i learn my lesson the hard way.

so what i did was after they renew my mac with a new hdd, 

i bought myself two external hdd,

one for time machine backup

and one for all my other files,

so i don't keep any master copy of data on my mac hdd anymore.