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Hi @GamerX, I am very sorry to hear about what has happened. 
I recommend that you contact your Local support in order to be assisted in sending the device in to service, that way a technician can have a look at it. I strongly advise against trying to remove the card yourself, since you could damage the device internally.
I hope that it did not take any damage, but as I mentioned above I recommend sending it in to an authorized service center to make sure it's removed correctly and in a way that the phone won't be damaged.
If it could get in, it can also get out! I'd simply try a magnifying glass and some tweezers. Perhaps some needles if it needs a little repositiong before the tweezers can get to it. Make sure to try and not touch anything sensitive in that SIM slot!
EDIT: sorry, just noticed you said you can't even see it anymore. Not even with a magnifying glass? If you really can't get to it you have 3 options:
- Let Sony repair it (best but most expensive option)
- Let some local repair dude repair it (cheaper but you will lose your Sony warranty)
- Open the phone yourself and get it out (cheapest but you will lose your Sony warranty)
If you still have a long warrantly period it might be worth to invest into having Sony do it. They can give usualliy you an estimated price for the repair.
If you want to give it a shot yourself, the best idea is to study some youtube videos on how to open the phone / get to the SIM slots et cetera, and get the right tools for the job.
If options 2 and 3 are not viable then go for option 1: ask Sony to repair it!
Perhaps you have some insurance that can cover the costs, otherwise it's bad luck my friend 
I have to admit though: that whole SIM/MMC slot module is quite poorly designed, accidents like this were bound to happen.