A flashing question mark means that the system cannot find a System Folder. Have you been able to start the machine up before? Also, does it sound any different (quieter) than it did last time you had it working successfully? With these older systems, a big problem is that the hard drives die easily, coming to the end of their life expectancy. Anyway, in order to do anything, you'll need a floppy disk with a System Folder on it, which you'll have to make with another Mac, such as the System 7.5 Network Access Disk. Provided the drive is any good, you'll also need a set of system install disks to install a system on there. What other equipment (such as CD-ROM drives) do you have that may make this easier? Also, do you have any other Macs?

Welcome to the forums by the way