Re: Electrical socket plates
First you have not posted if they are flush or surface switch sockets. I will assume they are flush.
Not sure why they would have turned grey in colour, however that suggests they may be old. Depending how old makes a difference as the screws could be imperial and not metric, so use the old fixing chrome screws. Also note some older swicth sockets had four front screws and new ones normally have two, one each side. Hence if side fixings are used for the first time you could bugger them up with incorrect thread screws or poor threads.
If older the wiring may be supple 7/029 and the job quite easy. Modern 2.5 is not forgiving and connections really poor unless you know what you are doing.
Depending on age the earth wires should have green sleeving, if it does not be careful that it does not touch a live or neutral connection when you push the socket back. More important when you push it back make sure that no cables will be hit behind by the fixing screws. If recent another earth wire is fitted to earth the metal box via the socket. Simple part just put the cables back in the same places as they were removed from as marked. L-N-E
All easy depending what idiot put them on in the first place and how many cables they tried to cram in the back and bodge.
All stuff any man should know.
Advice, get a boyfriend, working class as some like to call them, they understand what they are doing.
Sockets in France, they are another thing. Good Luck, with the boyfriend.