i am not able to go to bios setting or boot options,

[Ratnesh-]

i am not able to access boot options, even after pressing F2(may be different for different system)
it is displaying "pree F2 for setup" , but nothing is happening after pressing F2, i have no idea regarding this , please can anyone help me..

my current os is window 8.1

 

[johnbl]

I think some systems have fastboot enabled and you only get a short period of time to get into BIOS before the OS starts to load. You will get more time, some will not even get the option unless they power cycle the machine (turn it all the way off and back on). Most of the time you can just keep tapping the f2 key after you power on
(or what ever key your vendor decided to use to get into BIOS (f1, f2, del, esc, f10 are common)
vendor BIOS key mapping:
http://pcsupport.about.com/od/fixtheproblem/a/biosaccess_pc.htm

i am not able to access boot options, even after pressing F2(may be different for different system)
it is displaying "pree F2 for setup" , but nothing is happening after pressing F2, i have no idea regarding this , please can anyone help me..

my current os is window 8.1

 

[Ratnesh-]

@ johnbl ,
thanks for replying so fast ,day before that i tried to install ubuntu , and i had install easybcd to fix some boot options for ubuntu and window , but i failed in that attempt, due to some problems i reinstall window 8.1,
and now i tried to boot from usb i was not able to access bios setting.