I accidentally said i was claimed as a dependent, which i was not nor my parents did and i didn't receive a stimulus check, neither did they get my dependent credit

you have a few choices to correct this

1) send in an amendment to your taxes.  the problem is this will take at least 16 weeks for the IRS to process and there is no guidance whether they will send the stimulus check out immediately thereafter.. Maybe they will send the stimulus and maybe they won't - no one knows at this time

2) resolve it with your 2020 tax return next year 

• The stimulus payments are really based on your 2020 tax return (income, dependents, etc).
• The IRS is using either 2018 or 2019 – whatever is available  - to ESTIMATE that payment
• When you file next year there will be a “settle up” section on the tax return. 
• If you are due more stimulus (and this would include where you simply never received it), you will receive it through the 2020 tax filing as an additional refund
• If you received too much stimulus (not the issue here), by law , you are not required to return it