Last night my van made a sound and then the transmission locked in 2nd gear, the check engine light came on and the speedometer stopped working. Is this as bad as it sounds?

A malfunction was detected by the Powertrain Control Module and your transmission went into whats called the Limp in Mode designed to get you to a mechanic or home and not much more. If you can get it to Autozone or the like they will connect a scanner and read the fault code that turned on your Check Engine light free of charge. They can then tell you if an external sensor has failed or if there could be a more serious internal failure.

These transmissions are very sensitive to the fluid used. If there is anything besides ATF-3 or 4 in it or it's been years since the last fluid change get it flushed and refilled. Never use Dexron. Keep in touch.