Please don't worry. The medication you were prescribed is a combined oral contraceptive pill containing the active ingredients ethinylestradiol and levonorgestrel. Since it is currently out of stock, you can safely switch to any other birth control pill that contains this exact same generic combination in the same strengths (typically 30 micrograms of ethinylestradiol and 150 micrograms of levonorgestrel). They will work exactly the same way. Please consult your pharmacist or doctor to obtain the appropriate generic equivalent. If you experience any delay or gap between your pill packs, ensure you use a backup barrier method, like condoms, for seven days.