You can download a manual for a Frigidaire stove on Frigidaire's official website. If it's an older model, you may need to use a different source, such as Manuals Online.
In order to download a manual, you need to know the stove's model number, which is typically found in one of two places. With the oven door open, look on the left side of the interior door trim. If the model number is not there, and the stove has a storage door beneath the oven, open that and look on the front frame. The model number is typically about ten characters, including letters and numbers.