can not access boot menu :(

    *  Turn off the PC. Hold down the {Insert} key and then turn the PC on and wait for it to boot. On some PCs, this will clear and reset the CMOS memory for you. (On most PCs it will not work, so don't be discouraged.)
    * Try the same thing with the {Delete} key. Again, it usually won't work.
    * Look in your motherboard or system documentation for any evidence of a CMOS clear jumper. This is a jumper on the motherboard that can be used to clear the CMOS memory; many newer motherboards have them. Follow the instructions for its use as described in the documentation; usually this means opening the PC, changing the jumper to a special setting, and then booting the PC. The CMOS memory will be cleared. Then you power the PC down and put the jumper back to its previous position. If it doesn't work properly when you try it, look here.
    * If you do not have a CMOS clear jumper, your next option is to try disconnecting the CMOS battery. This is easy to do if the battery on the motherboard is removable or user-replaceable. If you see on the motherboard what looks like a flat round wristwatch or calculator battery in a holder, that's it. Some older motherboards use batteries that sit off the motherboard and connect with a wire. If the battery can be disconnected, then disconnect or remove it. Wait for about two hours (you may need to vary the amount of time; if two hours isn't enough, try leaving it overnight) and then plug it back in, and the CMOS should be cleared and reset.
    * On some systems, the CMOS battery is integrated within the BIOS chip. You may have success with removing the chip for a few minutes and then replacing it. Just be very careful to take anti-static precautions.
    * Your motherboard may have a battery that is soldered to the motherboard. You may not see a battery on the motherboard at all; if this is the case then your motherboard probably uses a battery that is integrated into the real-time clock chip (or else, you weren't looking closely enough :^) ). Unfortunately, on a motherboard without a removable battery and with no CMOS clear jumper, clearing the CMOS memory is difficult to do. At this point you should contact your manufacturer for technical support.