Windows 7: Boot manager missing enter ctr_Alt+del to restart.

hello,
i just installed a new window 7 ultimate os to my 32 bit system..
and i doing something with my disk management ..i actually delete the 21mb un allocate space in my disk management.
after that i do some my work and browse the internet and shutdown the system .
but when i again starting my computer ..it will nor work ...only a message appear on screen ...

boot manager is missing ..
press cltr+altr+del to restart...

again and again only this message ...

i try to go boot manager by pressing f2 ,f12,f8 it it doesn't work....only pressing delete button it shows some options...
it try to install a new os but it is not reading my cd/dvd or usb....
when it check options it shown a massage that they are disable ...

so plz suggest some stuff to enable my usb ,dvd port...
or any way to start my system....

thank you

Do a Startup Repair:
Startup Repair
Note: You may need to do startup repair 3 to 4 times.
Startup Repair - Run 3 Separate Times

Using the fixes in the microsoft article beow may help and prevent doing a repair install please work thru them.

Use the Bootrec.exe tool in the Windows Recovery Environment to troubleshoot and repair startup issues in Windows