I'd left a floppy disk in my computer and when I turned it on it read the disk and said "invalid system disk, or disk error. Replace and press any key." Anyway, I took the floppy out and pressed a key and nothing. I restarted the computer and this time I just got the cursor up in the upper left just blinking and doing nothing. The computer still tries to access the floppy disk but I won't boot up. Can anyone help with this please.

Firstly, put a boot disk in the floppy drive and see whether it starts. Then go to C: and see if it is there (if it is, you are lucky).
You may have either a virus attack, a corrupt FAT table on the hard drive or in the BIOS the hard drive values had been cleared (any option has a fair chance to happen). Obviously, it may be that your hard drive died (it also happens more often that one thinks).

do you have a bootable floppy disk? try these dos commands:

sys c: = restores bootsector & system-files

fdisk /mbr = restores master boot record

scandisk c: /surc = surface scan of your boot hdd (if sector 0 and/or 1 is bad, your hdd is not bootable for DOS-compatible OS's anymore!)

good luck!

I believe FDISK /MBR deletes the Master boot record so you can SYS C: to an empty space.

As fare as I know using FDISK /MBR will replace the Msater Moot Recorde with a new one, Incase it was damaged. I use it at work all the time.