Be careful not to push too hard on the shifter, you can bend a shift fork. It sounds like you have a clutch problem. My first guess is that a clutch spring may have broken. When one of the spring tabs breaks, then the clutch won't fully disengage. It could also be the throw out bearing or hydraulic clutch. If you can verify that the hydraulic clutch is actuating, then the transmission would likely need to be removed to inspect the clutch and throw out bearing. If you don't have the capability to remove the transmission, I recommend finding a transmission shop in your area that works on manual transmissions.