Recent contact details disapeared iPhone 4

I was recently roaming on my iphone 4, and was replying to a text when i saw the name at the top change to a number?

A little later i tried to retrive a telephone number and the person that i was looking for was no longer there? Upon futher checking i found that a number of recently added numbers (back about 3 to 4 months) had also disapeared?

I thought that it may have been something to do with roaming in another country, but back home now and contact have still not returned.

About the same time back as above, i added a gmail (New job) account, and on checking in gmail i have found that the telephone numbers are also missing from my contact details within my gmail account, of the contacts that i set up since starting this account?

Icloud is turned on and when i checked my hotmail account the contact information is stored there?

How do i get it back on my phone?