What stepper motor is this?
Probe the coil arrangement out with an ohmmeter, and assuming that might be satisfactory for you, then compare the resistance and maybe inductance to catalogs of manufacturers with similar physical sizes to estimate the current and voltage requirements and likely performance. Don’t worry too much about polarity, worst case you reverse one pair to reverse direction, most likely.

Don’t push them quite that far to be on the safe side. You can find many DIY webpages on the different types of steppers and how they might be driven.  

If this seems like more work than it’s worth, then you can buy some Chinese steppers or surplus steppers from eBay etc. that have proper datasheets, but it’s not something we can or should do for you.