I know this is a cheesy answer but it is true. The signs of Allah’s existence is in His Creation. The Universe whom he beautified just so we could praise Him which shows how much He really does want to guide us, His Earth and the other planets, the stars etc. He has also given us examples of His signs like how plants grow or how the birds fly, how these things are done because of Him, how all sustenance is from Him. He also says His signs are the ayat of the Quran. What is written there was written by no human. The specific nature of the parables, the lessons taught by them, the countless miracles. In those verses are a sign especially if you read the Quran with the sincerity of wanting to know more about Allah. As for personal signs maybe. There are things that have happened not from Allah but because I was for example talking about Him. But those incidents I do not trust as much just because I don’t have the full knowledge of the unseen. However, from Allah, he has always been here for me. Even if He doesn’t answer my prayers straight away or they don’t come true later I’ll find it was for the best. My whole life has been a rollercoaster. I have not suffered in anyway like those who are oppressed or hurt etc and l cannot count the blessings of Allah however my life has not been easy for me personally especially mentally which then impacts my life directly or in stages, and the way it has sorted itself out or the paths I have taken even if they are unexpected makes it seem like someone is pulling the strings from above if it makes sense. However I do not realise that in the moment. In those moments I am far away from God and I regret it but He has always led me back to Him and I will always be grateful. If you are asking this question because you are having doubts I beg you to not let Him go just because He hasn’t sent a ‘sign’. Your life is a sign of Him. Allah has said in the Quran the reason why He doesn’t send miracles, like the miracles everyone wants to see, is because people still don’t believe in Him or they say it’s witchcraft. However, I believe He sends miracles to individuals in His own way and remember to be patient even if it’s difficult because that will only make your patience more worth it and more rewardful