Old system kicked up a battery has run out message so got new one.
But now it won't detect hard drive and kicks up this message:
Disk boot failure, insert system disk and press enter.
Inserted windows 98 disk and press enter but reads cd and off course won't boot up onto anything. Checked cables, but didn't touch em. Has it changed bios settings. Won't auto-detect drive in setup either.
Turn the system on. As it boots up, just before you get to the post screen, press the "del" key to enter the bios. Set the boot order to cd>hardrive. If the cpu fan is runnning fast, while you are in the bios, calibrate the "smartfan" setting and enable it. Then press f10 to save and exit. Then insert the windows cd and it should start loading.
likely HDD failure, it just so happened that went out at the same time with the battery. Keep in mind that HDDs have a limited life span, and judging from the Win98 thing, this one has lived it's life. You will need a reinstallation on a new HDD.
Alternatively, you can try to run Killdisk on this HDD (mount it as an external drive on another system using an enclosure or a dock and erase it); this will try to restore it to factory settings. It will not last long, though; in a few months you will have to replace it.
Mounting it as described will allow you to recover/transfer some files you might need from it, before wiping it out. There is a possibility the controller on it went bad, in which case it will not be mounted/seen even as an external drive. In that case, toss it and replace it.