Could be a couple of issues that you may need to address.
1) your breaks have seized due to rust and corrosion caused by the change in temp and weather patterns
2) you brake cylinder is inoperable
3) there could be a build up of broken down slug within the break line
4) your break calipars have malfunctioned
5) your half shafts have seized
If your comfortable DYI, than you have alot of work, however,replacementing piece by piece will save you in the long run. Start with the replacing the pads, fluid, and flushing the break line. Test and move forward with replacing equipment as needed.
If not, your going to end up spending a few hundred bucks in a shop.
If I think of anything else, ill send you a message.