iOS 8 running very slow. Can I reinstall iOS 7?

No. You are stuck where you are. Give a bit more detail and we may be able to help with specific issues you may have.

First off, try a device reset:

Device Reset (won't affect settings/data/music/apps/etc)

1. Press and hold (& continue to hold) BOTH the Sleep/Wake button & the Home button.

2. Continue to hold BOTH (ignoring any other messages that may show) until you see the Apple logo on the screen.

3. Release BOTH buttons when you see the Apple logo and allow the device to boot normally.

steve70inIndy wrote:

Thanks for trying to help. I think Apple should give me my money back!! Steve

Why would you think that?