startup problem

Hi
I am having problems starting up my Toshiba laptop
windows vista
Hard Disk Drive Hitachi HTS542512K9SA00(S1)
System BIOS VERSION 1.3

when i turn it on it goes through the Toshiba loading screen and then to Windows error recovery screen where i get two options
1. Launch startup repair (recommended)
2. start windows normally
when i choose option 2 to start normally i just get blank Grey screen
when i choose option 1 to start recovery i get a startup recovery screen giving me choice of "view diagnostic and repair details" which doesn't show up anything unusual and "view advanced options for system recovery and support" which leads me to "system recovery options"
1)startup repair- which tells me it is unable to repair and then shuts down
2)system restore - which tells me there is no restore point created on my computer(which i am almost certain there should be)
3)windows complete PC Restore - which tells me that a valid back up could not be found
4)windows memory diagnostics tool - which give me the option to check for problems next time i start my PC or restart now and check for problems which gives me blue screen where it checks for problems but nothing detected
5)command prompt
6) TOSHIBA HDD Recovery - when i run this i get an error message telling me "The computer restarted unexpectedly or encountered a problem and cannot proceed. To install windows click ok to restart the computer and then restart the installation" when i click ok i keep getting this message

I have tried starting the PC with the battery removed and using only AC power but this does not make difference.

have tried starting from "last known good configuration" & "In safe mode" & "Directory services restore mode" but all bring me back to the windows error recovery screen again

if i go to F12 boot manager and start from HDD or FDD i get sent back to windows error recovery screen also

 

thanks for rapid response
i don't have windows install disk

 

is there a command prompt that i can enter????

 

i would consider myself fairly technically minded but maybe not as technically minded as you guys maybe you could elaborate a little on how to do this