Try 88's suggestion first. See if the lever is attached to the cable. If so, see if the cable is attached to the latch by grabbing the cable and trying to pull it further than the lever would. If it pulls another inch of slack, she's busted and you may need to use creative force and sacrifice your grill to get at it. Even if the cable pulls on the latch, it is possible that the latch won't release of the mechanism is buggered. Have someone lift up on the hood while you pull the release. See if it pops up an inch or whatever then. If so, you can continue to open it from the front. Once open, troubeshoot the mechanism by latching on a D-ring or screwdriver (with the hood still up) and have someone else pulling the lever to see what's refusing to move. Maybe a good shot of PB or similar might free things up but I wouldn't trust it not to fail on me on a cold rainy day when a belt breaks and I can't get under the hood to fix it. That would suck.
If you determine that the cable has detached from the latch, post again and maybe someone with a 91 or similar can open theirs, examine the latch and mechanism and see if there might be a way to get at it from underneath or a way to get at it. Isn't one of us a former wrencher from a Nissan stealership? How would a dealer approach this?