Try with this:
grid = [[20, 21, 22, 23, 24],[15, 16, 17, 18, 19],[10, 11, 12, 13, 14],[5, 6, 7, 8, 9],[0, 1, 2, 3, 4]]def celdas_vecinas(cell,n): Row = [-1, -1, -1, 0, 0, 0, 1, 1, 1] Col = [-1, 0, 1, -1, 0, 1, -1, 0, 1] x = y = 0 for i in range(n): z = 0; for j in range(n): if grid[i][j] == cell: x = i y = j z = 1 break if z: break ans = [] for i in range(9): xx = (n + x + Row[i]) % n yy = (n + y + Col[i]) % n ans.append(grid[xx][yy]) return ans;print(celdas_vecinas(1,5))print(celdas_vecinas(21,5))print(celdas_vecinas(5,5))