cannot found drive

Hello friends when reading Malay Akechan (admin) on how to hide any drive i see perhaps you could solve my problem.I have 2 harddisk in my dell 2400.local(c:) works but cannot found (D:)&(E) for a long time.When boot F2 on drive config put primary slave drive & secondary slave drive off IDEdrive UDMA on.last month i see D&E the day after nothing.I just see the drive again last week but now nothing.I have Avast antivirus.When enter command prompt>diskpart>list volume see only vol 0 letter F dvdrom volume1letter c local disck,also when right my computer >properties>device manager>hardware>IDE ATAL/ >properties on primary ide channel cannot enable or disable the device(space blank).Advance setting Device0=devicetype blank.Transfermod=Dma if available.Current transfer mod=ultradma mod 2 .Then device1=device type :auto detection.Transfer mod=PIOonly.Current transfer mod= not applicable. Secondary IDE channel can enable &disable.Sorry having a bit long.I need some help.