A white candle can be used for any spell, because white is the essence of all colours. Candles usually are to help with communicating with a certain god or goddess in a spell. Also candles can help to show a god or goddess respect :)
White candles can be programmed to be any other color candle .White is very spiritual color linked with life and dead .Many people have as working candles white candles .You can use candle for fire scrying ,as working candle or while casting spells for spiritual growth .It kinda can be used for all purpuse .White one as used for purity ,cleansing ,truth ,spirituallity and some people use them for blessings or selfblessings .Also many people leave candles on the windows to guide the soul of the dead for Samhain .This are just one of the possible uses of that one single white candle .From now on it is up to you how to use it .Have a fun .
You could use the candle to influence a friend to contact you that you haven't heard from in a while.
Take some olive oil/vegetable oil in your hand, visualise the outcome you want which would be the person contacting you while stroking the oil onto the candle, saying "contact me" over and over while you do it.
There are many things you can do with a white candle since white is a color that can be used as a substitute for any color. Candle magic can involve carving symbols into the candle to aid in the casting, anointing the candle with an appropriate oil and then charging the candle with energy prior to lighting it. What you use depends on what type of outcome you are shooting for.
For a protection spell; Carve the name of the person you wish to protect and some protective symbols such as the pentagram, the protection rune, or anything else you deem as protective. Then anoint the candle by rubbing it with a protective oil such as pine or basil. Leave the candle to charge on an alter or in a special place for at least a few hours. When ready light the candle while thinking of the outcome you desire. Keep your thoughts simple and to the point. Leave the candle to burn until it burns it's self out. If you need to put it out do so by snuffing it and then re-light it when you can.