Just saying that the sidewalk was uneven, is not enough. Depending on what the actual condition was, it may give rise to a valid claim. However, it is also significant as to whether this mishap occured on a private school grounds or a school owned and/or operated by a governmental agency/authority. In the latter instance, there can be statutes which may impose specific requirements that have to be met to be able to sue that school and/or governmental authority, with shortened periods of time to file "notices of claim", etc. You need to consult with a local attorney, which should be provided to you free of charge. Parenthetically, if your injuries are limited to what you describe, and assuming that you are not left with a truly disfiguring scar, the chances are the amount of compensation you could hope to obtain even if successful in holding the school liable will be outweighed by the time and expense incurred in prosecuting the case. Good luck.
Consult a local injury atty. Pictures and measurements of the exact spot where you tripped need to be made before the area is changed or fixed. Claims against govt entities usually have short time requirements, so contact the lawyer asap. Get photos of your injuries and all needed med care.
It depends on the condition of the sidewalk and the owner/operator controlling the sidewalk. You may need to hire an expert engineer too. Bring all of your medical records to a local personal injury attorney for an evaluation. Good luck.
The above is general information only and is not legal advice. The information provided does not form an attorney-client relationship, and should not be relied upon to take or refrain from taking any action. I am not your attorney until we sign a retainer agreement.