Undected Operating Systems

My husband used the PC, shut it down per instructions. Next day, I start to run PC (have a homebase business) and it tells me that it doesnt detect an operating system. I had Win95/98 and all of the Microsoft Windows 2000. I tried scandsk and it tells me I have no problems on the c:/. Yet, when I go to the msdos prompt-it says i need to partition. I dont have any data and my business is on standstill.I need a mentor also to partner on gov/city/county/fed procurement.