My PC wont start.

I have a hp pavilion running windows xp sp2.
When i turned it on today, it went through the memory check as usual, but after that nothing more happens.
all I can see is a white flashing: ” _ ” up in the right corner. i have restarted several times. but nothing works.

And i dont know to start in DoS with HP’s poor BIOS.

+ i do not have a boot disk.

thank you