How do i get my 98 volvo s7o to shift up past 2nd and fix the speedometer

since they both work off the speedometer cable/electrical and the odometer still works this sounds like the speedometer head is bad and needs either repair or replacement.

Low transmission fluid. or Bands in transmission worn out or out of adjustment. Get transmission serviced ASAP

Your car reads off of the trans. Sensors to shift. You are going to need an input and output sensor, that will fix your speedometer also.

Is the speedometer working?

if the speed sensor is bad the spedo will not work and the tranny
will stay in low.

That sounds like a Vehicle Speed Sensor (VSS) problem to me.

VSS can be bad and the 3 & 4 shift solenoid can be bad. Get a free computer test scan at any Auti Zone to confirm my findings

spray ignition with graphite

check your fues box were it say gagues

The cheap fix: Speed sensor connected to the Transmission Control Module (TCM). That screws up the engine control module and could throw you into limp home mode. Expensive fix: Transmission control module. Start with the speed sensor. Suggest that to your mechanic and get a second opinion before changing out the TCM. It's a simple plug and swap, but the module is expensive. I bought a spare on Ebay for my Volvo for $10. The TCU, I believe, lives under the right front kick panel, at least that's where it is on my 740.