This is really a question for ARRL. Here is what I found:
http://www.arrl.org/renew-certificate
It basically says that if you renew your cert before it expires, it is easy. If it expires, you have to request a new cert.
I couldn't find much on "lost certificate".
http://www.arrl.org/file...our%2520Certificate.pdf
This basically says if you lose your private key password, you will need to apply for a new cert.
You will probably have to call ARRL. I have talked to people in the LoTW dept and they were quite helpful.
I do not think your current QSOs will be lost. If they are, no big deal, they are still in LOGic, right? Just upload them all again.
Sorry I can't be of more help. When you figure out what to do please post here so we all know!
Tnx & 73,
DH