Sawsall
a pry bar
Check parking brake if you use it. Sounds like broken cable.
You can take the front grill off, with some T20 screws on the front of the car. You will see the hood release cable, and the mechanism that it attaches to. Just look at it, and you will be able to figure out how to open it from there.
Zorro - 1990 Broken Heart Broken Mask 2-9 was released on: USA: 9 November 1990
If it feels like the cable isn't broken, pry up on the hood while someone is pulling on the release. If it doesn't work, take it to the body shop.
This may help other 964 owners with broken rear lid cable ,sussed this out myself raise rear spoiler to expose engine bay get a old metal coat hanger make a loop one end hook onto release mechanism, hey presto off it pings!
Broken Badges - 1990 Pilot 1-1 was released on: USA: 24 November 1990
Broken Badges - 1990 Chucky 1-2 was released on: USA: 22 December 1990
Climb under the front of the engine compartment with a coat hanger and a flashlight, reach up and grab the latch and pull it down.
Broken Badges - 1990 Westside Stories 1-3 was released on: USA: 1 December 1990
You can do this buy removing the plastic front radiator grill. You need to remove indicator lights, then the middle screw, then with a small flat screw driver release the plastic clips just underneath the bonnet. Then put your hand behind the bonnet catch and pull the broken cable or the latch and it will open. Good luck
Seeing it's a 1990 model it probably has a speedo cable. Either it's the sending unit on the transmission, the speedo cable, or the gauge in the dash. You'll want to try to get behind the gauge in the cluster. Disconnecting the parts can be a pain, take your time. In fact make sure you get a guide or something, cause it's bound to have hidden screws and parts. Once the gauge is removed from the cable, drive the car briefly forward to see if it spins. If it doesn't, then you know it's further down the line. Sometimes the cable can bind up and break. Personally, i'd say the likely hood is 1)broken cable 2)broken gauge in cluster 3)broken speedo gear in the tranny. Best of luck!