communication

is there any pre-defined/written project scope? if not, ask the boss to clarify. Maybe he/she do not expect you to finish everything in one-shot. most of time one can take incremental approach.

Normally there are three main road blocks: lack of resources, lack of understanding of the problem (lack of business knowledge), or technical challenges. It is not your fault if any one of those factors challenges the project. But you have an obligation to let boss know.

Figure out what the main issue, and communciate to the boss, the early, the better. The worst thing one can do is, wait till the last minute for the boss the find out that the project can not succeed, without appropriate communication.