I had same problem recently. All I can say is once you get it back together you kick yourself for not figuring it out more quickly. Took me about an hour to work it out but it is fairly intuitive the parts only go back together one way.
You put together the lever, small spring, plate and the stubby bit then bring it up through bottom of the lever body. Then the big spring goes on around it you have to wind up the tension by pulling the lever clockwise then hook up the other 2 springs into their respective holes and hold it all together whilst you insert the shaft through and tighten the nut on bottom of lever.