What should someone do when they don't know if they have committed kufr/shirk? Like when they don't know if what they thought was waswas or their own thoughts, or when they're not sure if what they believe/do is kufr or not, or when they think what they thought/did might have been kufr but they forgot what it was? Should they repent and renew their Shahada to be sure? And would they have to repeat their wudu' in this case? I often wonder if what I said was kufr right before prayer, during wudu' and so on and I don't know if I would have to repeat my wudu' or if I can just pray anyway. Note that it's not always waswas, sometimes I intentionally think something but don't know if it was kufr or not and I don't want to delay my Shahada (as I think that's kufr in and of itself, isn't it? Because I thought delaying Shahada means that you're content with kufr, a'uudhu billah).. I don't know what to do in these situations. Normally I just say the Shahada to be sure, but I'm not sure if that's the right thing to do.
All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
All of this is mere satanic whisperings (Waswaas) that are unreal. You should ignore them and pay no attention to them at all. Do not accuse yourself of committing Kufr based on such whisperings and thoughts. You are a Muslim; all praise be to Allah, so be decisively certain of that. Do not dwell on these whisperings as this leads you to grave evil. Do not recite the Shahaadah (testimony of faith) with the intention of embracing Islam because you are definitely a Muslim, and such whisperings do not affect your Islam. The only remedy for these whisperings is to ignore them completely.
Allah Knows best.
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