Flooded my kitchen! Urgent help with u-bend please!

[Melon6412]

Can someone please, please tell me what I'm doing wrong!? My kitchen sink was blocked so I took the u-bend apart, didn't realise for even 1 second how much water would gush out and naively put a small bowl underneath to catch the 'drip'. Cue massive rivers of water. Ok, I deal with all of that, clean the u-bend and then go to put it all back together. I noticed one of the washers was completely damaged when I took it apart, I'm not sure if that matters. I've put it all back together and water keeps leaking from different joints in the pipes, I will hopefully add pictures, including one of what is assume is the washer.

What am I doing wrong? And while this is all leaking, am I still ok to use the shower, washing machine, toilet etc or am I going to cause a tsunami with my 3 children asleep upstairs!?

Utterly lost and no longer feeling proud that I 'unblocked' my sink.

You need @pigletjohn.
Other than that I have no practical suggesting.

If it's been in place for a while, the black washers/seals tend to go hard and slightly misshapen, so they often don't seal back up again properly.

However, the dirty white curl in your pic looks like someone's just given up and thrown silicone sealant at the problem. So there's either a damaged seal in where that was, or no seal, or the pipework is iffy and won't ever seal.

Plumbing work sucks in general, but what you've got there has been done pretty badly, that flexible hose at the bottom is wrong wrong wrong! I'd be very tempted to get an actual plumber in to sort it all out properly.

Anything not directly connected to this will be fine to use - looks like you've got a double sink (will spill) and one dishwasher/clotheswasher attached here? Don't use that either.

Shower/toilet will be fine.

Whatever's coming in from the very bottom left will also be fine - that's below the leaky section.

@SpoonBlender, thank you so much, I'm relieved we can use the shower etc. It is a double sink yes and it's only about a year since it was all fitted.