Yes, you need to take your daughter to see a physician immediately, even if that means going to the emergency department. Eye problems are serious concerns that should not be taken lightly, as they can result in long term complications that can affect your eyesight for the rest of your life.
With the limited information that is provided in your question, it is difficult to understand what is happening (another reason to take her to see a physician immediately). Commonly, extra secretions from the eye caused by common eye infections will cause the eye to be difficult to open. These secretions can often be removed or softened with the gentle application of warm, moist heat as with a gently warmed wash rag. If the secretions are this significant, than you should speak with your doctor
about treatment options. Alternatively, your damage to any of the nerves that affect the innervation of the muscles surrounding the eye can be another cause for not being able to open the eye. As you do not provide the age of your daughter or describe any antecedent trauma, it is best to take your daughter to a physician immediately for an initial assessment and recommendations.